ZuzuLily, there are several possible causes, so there are several possible cures. Here is a list of cures that I have accumulated:
Folks, so many people are having trouble with the Start Button not working in Windows 10, that I have assembled all the various cures. None of them will work every time, but there’s a good chance that one of them will.
1) Go to this web page
http://home.bt.com/tech-gadgets/computing/has-your-windows-10-start-menu-stopped-working-here-are-four-ways-to-fix-it-11364000314532 to learn how to use PowerShell (a built-in Windows utility that you already have) to fix it. His first two ideas are pretty good. Don’t do his more drastic solutions, though, until you try these other ones.
2) Uninstall your anti-virus program and re-install it.
3) Simply use the Windows key (between the Ctrl and Alt keys) instead
4) Type “Classic Shell” into a search engine and install it. It is a free Start Button that works great.
5) Use System Restore
On its official site, Microsoft recommends:
Method 1:
1 Open run command. (Windows logo + r)
2. type
regedit and press
enter.
3. click
ok when notification window prompt.
4. Go to
HKEY_CURRENT_USER>Software>Microsoft>Windows>CurrentVersion>Explorer>Advance
5. Create a Dword with name ‘
EnableXamlStartMenu’.
6. Give it value
0
7. Log off and login again.
If it still doesn't work try these methods.
Method 2:
I would suggest you to try ‘sfc scan’ if you haven’t tried it yet.
Let’s use the System File Checker (SFC) tool to see if it can find any missing or corrupted system files. If so, it will attempt to repair and/or replace them. Follow these steps:
1. Press
Windows +x
2. Select
command prompt admin.
3. At the command prompt type “
sfc /scannow” (no quotes), and then press
ENTER
Method 3:
1. Press
Windows + x
2. Select command prompt admin.
3.
Type dism /online /cleanup-image /restorehealth
4. Reboot PC.
MS Troubleshoot also has recommendations at
http://windows.microsoft.com/en-us/windows-10/get-help-windows-start-menu