any error messages?

If it works when running as local admin, it could be due to security policy changes for the user account. My first suggestion would be to reinstall FME and see what happens.

Also, please post any screenshots or error messages here.

"File Couldn't open "

Attached both screenshot one is FME workbench and one is FME command line using fme.exe

Are you able to open the .fmw file in e.g. Notepad without running as local admin? If not, it's most probably the file permissions that needs adjusting.

Yes I am able to open fmw file using notepad. something wrong with fme.exe file i tried giving all permission still same one.

If you look at the exact error message on the command line, it looks like fme.exe is trying to open the folder rather than the file.

Try putting double quotes around the complete filename on the command line, e.g.

fme.exe "d:\path\to\my\workspace.fmw"

Can you try opening a different workspace file. Also try to first copy the workspace file to e.g. your desktop and open it there.

It could of course also be that the workspace file is corrupted, somehow. In that case you should consider sending it to Safe support.

I tried opening any workspace in FME workbench also same issue. I tried with double quotes also same issue.

Could it be that for some reason the drive isn't mapped anymore? or there is something wrong with the mapping? is it a network drive or just a local drive?

It is just local drive. but while running notepad.exe same file can be opened.

I definitely remember this issue from the past but I've competently forgotten what needed to happen to fix it. Might be a reinstall you have to try :-/