Calibre Portable no longer starts up

I am running Calibre Portable 2.7.2.00 on my Windows 7 laptop & until today it has been working flawlessly for quite a few years.
No matter how I try to start it from desktop or file manager it refuses to load the program.

Do I have any options to get this running again or would it be easier to just install the install version & some how merge my setup into it?

Any suggestions would be greatly appreciated.

Thank you
Mark

What I ended up doing was extracting the settings folder from an older backup image I had and replaced the settings folder in the portable Calibre folder with it & now everything is working.
Something must of messed up the settings folder apparently.
What I have no idea.

Thank you to everyone who made suggestions.
Mark