Unable to open excel or word after a restore

Hello!
I've had problems for last couple of days with duplicate drives appearing in the navigation window. After trying lots of things I decided to restore to before the last windows update. Everything seemed ok until I tried to open Excell, I get an error message "not enough memory to complete this task etc." I have 6gb ram and 75gb spare on the "C drive", I've since tried Word and it's similar no error message but will not open correctly. Any ideas please?

Run the Office installer and try the repair install option.

Thanks, Steve.
I've done that, however I have had to revert to a copy of Office 2003.
This is because the copy of Office 2013 was when Microsoft offered a free update online.
I didn't have the product key and the Office 2003 key is not acceptable.
Anyway the original problem I had has now returned, the duplicate drive entries in the navigation pane under This PC.
Cheers,
Colin

If you have a Microsoft account (i.e. use outlook.com for email) your product keys for Windows and Office 2013 will be there!

I had troubles with all of the MS Office files after 1709 upgrade but clicking on repair took care of everything.

Thanks for the replies,
I installed Office 2003 and it's updates.
Then I found the original Office 2013 link and it's keycode on a CD.
So I removed Office 2003 and re-installed Office 2013 and everything is now fine.
Silly me, should have just clicked repair and not online repair, then everything would have been ok!
Cheers,
Colin