Misisng itunes songs after changing the pc's username and folder

Hi all,
I need help. I have Windows 7 Last week, I changed the account username and folder name of my pc. I also changed the user's registry to match the new name.

I am now having issues with my itunes. The songs are now mising and I checked their file path and they still have the old name of my pc which I think is the reason why I cannot play them. I tried to locate them one by one and it worked however if I continue locating them per song it would take me forever.

Also, I've noticed that some of the songs are really missing and their file paths direct to the old username.

Can anyone help pls? Thanks. :)