Undo won't work MS Word 365 on Windows 10

The problem isn't "Why I can't start my office 2013 application." The problem is the UNDO button won't work, and the program keeps crashing and losing changes. Since Windows 10, Word (Office 365) has become jerky and unresponsive thirty or more times a day. The screen locks up. Hours of work are erased because it isn't recovering the files. And this is with my setting of autosave every two minutes. Even though, when I press the file tab, Word shows my file saving every two minutes, when the program "white screens", for lack of a better term, I know that I've lost everything I've done since my last hard save.

I have the invite to upgrade to Office 2016, but I'm scared the glitches there may be worse. If I can't get this fixed, and fixed soon, I will have clients whose edits are incomplete, therefore losing income.

Possibly a dumb question, but is there anything to be undone?  When you first open a document, the Undo button is always disabled.  It is not until you have changed the document in some way that there is anything to be undone and the button should then become enabled.

It that was a dumb question, then, you might remove all traces of the Office installation by downloading the fixit from the following article:

http://support.microsoft.com/kb/2739501

saving it to your computer and then running it.

Then reinstall Office by logging into www.office.com/myaccount with your registered email address and click Install Office.

BEFORE REMOVING THE OFFICE INSTALLATION,  MAKE SURE THAT YOU ARE ABLE TO LOG INTO YOUR ACCOUNT AND THAT OFFICE IS ASSOCIATED WITH IT!

If you actually have Office 2013 (locally installed) rather than the subscription version provided through Office 365, then you can't get Office through your Microsoft Account. Instead, see https://products.office.com/en-us/download-back-up-restore-microsoft-office-products

I can't speak for Kathryn, but the undo button doesn't work when I've typed or deleted text within a document while in the midst of it.

It isn't that it just isn't present when I open a doc, obviously it wouldn't be highlighted if I have no words that have been altered.

I have yet to attempt to uninstall and reinstall, but I guess that's my next step. After which, I fear, I'll have the same returning problem as Kathryn did.

And to be clear, I have Office Professional Plus 2013.

If you have Office Professional Plus 2013, it will be locally installed and you will need the Product Key to re-install it.  Make sure that you have that before removing your present version.

Before uninstalling and re-installing, I would try repairing the Office installation as detailed in the Knowledge Base article at:

https://support.office.com/en-us/article/Repair-an-Office-application-7821d4b6-7c1d-4205-aa0e-a6b40c5bb88b?CorrelationId=1b0030f4-8cc5-4485-b495-810e2a7d1284&ui=en-US&rs=en-US&ad=US

Also try starting Word in Safe Mode by holding down the CTRL key while starting it until asked to confirm that you want to start it in Safe Mode and see if the problem then exists.  If it does not, it indicates that there is probably an Add-in that it causing the issue.  I would also try renaming the Normal.dotm template to Normal.old and then restart Word and try again.

No dumb questions, remember. When I open a document and work, the UNDO stays grayed out, as in, at no time does it work. It will turn blue for a scant second before graying out again. When it is blue, if I click it, it doesn't work.

I use Office 365 on the annual subscription. I uninstalled and reinstalled yesterday, but will do so today, using the Fix It option. Fingers crossed it works, because I'm really getting tired of losing hours of work when Word freezes without recovering.