Is this a registry issue?

hello, this computer is x86, running Windows seven Intel dual core processor. I am the only user. It runs fine and have no real problems with it - but something quirky has happened today. When I click on a shortcut for my Download folder, or on the 'User' folder, or a file within, say, 'Tools' situated on a different drive, my music app (Media Monkey ) opens instead. it is no big deal because I can open these other folders in different ways, but I do not understand why this is happening or how to correct it. There used to be a shortcut fixer native to Windows - is there still such a tool do you know? I have tried uninstalling-reinstalling MM, I have checked for malware via Webroot, and Malwarebytes is on realtime so should have picked it up if there was anything on here - but really I think this is more likely a corruption somewhere. When I ran another app for shorcut fixes it found 67 needed fixing. not sure if that is hyperbole or a real issue, but SOMETHING is wrong!

ICIT yes, I will run sfc - was going to get round to it, just not done it yet. I have already checked for malware but did not really expect to find any as the real-time sensors would have picked it up already. Thanks

thanks Callender, will give it a try.

it seems to have worked Callender - I forgot you said to merge the .lnk, and I merged the directory extension instead since it is folders that seem to be linked - but it seems to have solved the issue, and now I have the zipped file to refer to if I need to use it again - thank you.. I still wonder why it happened. :)
ps that toolbox site is awesome, have bookmarked - move over MajorGeeks!

thankyou ICIT, sfc did not find any issues and no malware present - Callender's suggestion about doing a registry merge for default extensions did the trick, so all sorted now

thank you for the advice ICIT. Appreciated.