Help Needed: EXS24 wav not found

Hey guys, this is my first time posting here. Sorry if this problem has been addressed before but I'm just not good at these technical "file&folder" stuff.

Basically the picture below is the problem I'm facing. The sound was there yesterday when I was composing but today its gone. I've been using LPX for a couple of years but this is the first time I've encountered an EXS24 problem.

Any advice to solve this issue will be greatly appreciated.

Thank you!