I think an update may have created a network problem on Artful ardvark. How do I delete the last update? I can't connect to a network to update any patches.  I can not connect to a wireless network. I used to be able to connect and then a few days ago it started disconnecting and reconnecting. After that it would no longer connect. I could connect to a wireless printer and print. I need solutions that don't include connecting to the internet to update or get any packages as I can't do either.
This has happened to me many times in the last 5 years: an upgrade broke my system. Each time I end up with this situation, I have to reinstall the whole system, which is really annoying.  Is there any way to roll back the most recent upgrade to be able to have a functional system without reinstalling? If not, which is the best way to suggest this as a top priority idea?   I read this idea was described in brainstorm.ubuntu.com, but it feels it is dead... and the forums are full of examples of upgrades breaking things, that's why I feel something needs to be done about this topic. Thanks!
Construct a fourth circle tangent to 3 circles forming a tangency chain How to hear my voice in speakers with a mic? Lost passport with Schengen visa What does bookmarking a question mean? How do you bookmark a question? Do users get updates on their bookmarked questions? Are my bookmarks publicly visible? How do you see your own bookmarks? How do you see other users' bookmarks? How do you see which users have bookmarked a particular question? What impact does the bookmark system have on the voting system? Can I &quot;un-bookmark&quot; a question? Can I search within my bookmarks? How to Send Html Emails in Google Spreadsheet Here's an example of a Google Docs Spreadsheet script that sends emails using Google spreadsheets. I want the email Sent in HTML not plain text. Can someone help me out?  function sendEmails() {   var sheet = SpreadsheetApp.getActiveSheet();   var startRow = 2;  // First row of data to process   var numRows = 2;   // Number of rows to process   // Fetch the range of cells A2:B3   var dataRange = sheet.getRange(startRow, 1, numRows, 2)   // Fetch values for each row in the Range.   var data = dataRange.getValues();   for (i in data) {     var row = data[i];     var emailAddress = row[0];  // First column     var message = row[1];       // Second column     var subject = "Sending emails from a Spreadsheet";     MailApp.sendEmail(emailAddress, subject, message);   } } pkgloader is not finding l3regex Prove that $\sin(\theta) + \sin(\theta+2\pi/3) + \sin(\theta+4\pi/3) = 0 $ for any angle $\theta$.   This came up in the context of electricity:  It is common in electrical power engineering to use three-phase circuits with sinusoidal currents out of phase with each other by 120 degrees. The benefit of this is that the currents sum to zero at the neutral point meaning less copper is required for the system.    However, while I know that the three phasors always sum to zero, and can see visually, as in the figure that this is true at every point, how can this be shown more formally, or algebraically? Shutdown and User button missing in panel I faced with a problem after update,   I missed 2 buttons from above panel, System menu (including shutdown, suspend &amp; …) and User (including log out &amp; …)  how can I restore them !?... Is the word "management" singular or plural? How to correctly specify coordinate system? Using QGIS v. 1.9 (1.7 does not seem to be available for Ubuntu Linux 12.04), do the following:   Create new project, specify coordinate system by clicking on button in bottom right hand corner, enable on the fly CRS transformation, set projection to WGS 84 / UTM Zone 18S. Pass mouse over project window and UTM coordinates appear in coordinates window in status bar at the bottom. Add delimited text layer in decimal degrees. When asked for projection, specify same projection as in (1). Points in the layer are plotted but, mousing over the map, the coordinates in the coordinates window are now in decimal degrees (even though the projection is set to UTM).   Is there something I am missing here? I have tried doing this in so many ways, so many times, but the result is always the same. I seem to be setting the projection correctly but only decimal degrees show in the coordinates window.  With thanks, Martin Is there a reason why we gain ghost reputation on the meta of an SE website? Is there any reason behind the ghost reputation we gain on the meta of a Stack Exchange site? This reputation doesn't add up to anything, but it still shows me I have gained some. Is this supposed to make any sense? Computing matrix-vector calculus derivatives $x, a$ in $\mathbb R^n$, $A$ in $\mathbb  R^{n\times n}$. Compute $d(x^T a)/dx$ and $d(x^T A x)/dx$.  I'm not sure about how to think about these and how to do these. Can someone explain how to derive the expressions for the two?  Finally, what happens when we have $A$ and $X$, BOTH in $\mathbb R^{n\times n}$, and we want to find $dTrace(XA)/dX$? Did this character even qualify for being Azor Ahai or The One Who Was Promised? In the books and to some degree in the show as well there is a prophesy about the legendary figure Azor Ahai. But in the latest Game of Thrones episode (S08E03) we see Arya      killing the Night King.   However in a  we discussed​ all possible candidates but nobody thought about Arya. Does she even fulfill the prophecy? If she does, how? How can I animate an object fading out? The exercise is: Prove that $-(-v)=v$ for every $v \in V$  Proof Suppose  $v \in V$ and $V$ is a vector space. Then $-(-v) \in V$ as result of the scalar multiplication property and $-(-v)=-(-1\cdot v)=-1 \cdot(-1\cdot v) =(-1 \cdot-1)\cdot v = 1 \cdot v = v $ The desired result $-(-v)=v$ holds.  The solution manual gives the proof:  Proof   I just wanted to make sure that the way I did the proof isn't missing anything?Thanks How to remove app icons in system tray on Ubuntu 18.04 with GNOME How can I remove the apps in right top corner (Google Chrome, flux, TeamViewer)?  Before my update from Ubuntu GNOME 16 these were even more annoying in the left down corner. How can I create and extract zip archives from the command line? How can I integrate $$\ln \left( x+\sqrt{1+x^2} \right) $$   The problem is from IA Maron Calculus, Problem 4.3.17. The problem is under the heading 'Integration by parts'. I have tried it, but it just leads to 2 unsolvable integrals Confused About Trigonometric Substitution There is a bar of chocolate of size $N$ x $M$. Little square $(x, y)$ is poisoned. There are 2 players taking turns. In each move they can cut the bar along any of the horizontal or vertical lines, then the part which does not contain $(x, y)$ is being eaten. The player who is left only with square $(x, y)$ loses (beacause it is poisoned). Which player has the winning strategy? I guess that this game is equivalent to game of Nim due to Sprauge-Grundy theorem, but I don't know how.