Hello binngokute and welcome to Seven Forums.
I'm a little confused why you reinstalled the operating system to try to repair Microsoft Office. In Office 2003 (the version I have at work) you could click on detect and repair in the help menu. Office would then try to find and repair problems such as missing files and registry settings associated with all installed Microsoft Office programs. Does your version of Office have that option? Automatically repair Office programs - Excel - Office.com
As far as Windows Explorer stopping you might try to run a System File Checker scan. If any problems are noted run the scan 3 times rebooting in between each scan. SFC /SCANNOW Command - System File Checker
If the SFC scan doesn't help you might consider a Repair Install. Repair Install
Please post back to let us know if anything helped or if you're still having problems.
Added Info: If you're using a later version of Office you might want to try Start > Programs > Microsoft Office > Microsoft Office Tools > Microsoft Office Diagnostics to find and repair problems.