I have this MacBook Pro running OS X Version 10.9.5 and it works perfect in every way except for one thing; it will not get updates. When I go to "About This Mac" and click on "software update" it will close out the window and --that is all. I am back on the desktop. there is no error messeges, or anything. Any ideas what I can do to fix this?
Three things to try - report back & we can tweak this answer.
Try Launching App Store directly from the Applications folder, rather than via About this Mac.
Clean out the App Store prefs & caches...
Open Terminal & copy/paste each of these 3 lines, hitting Enter after each
and again for the caches
rm -r ~/Library/Caches/com.apple.appstore
rm -r ~/Library/Caches/com.apple.storeagent
Make a new admin account...
System Prefs > Users & Groups
Unlock the prefs, if locked, & click the plus button at the bottom.
Set up a new Admin [not Standard] account, then try logging yourself out & into that account instead.
Test method 1.