Your best bet is probably googling "Excel password" and seeing what comes up. There are MANY many utilities out there for finding out the passwords in a spreadsheet, and you should be able to find one that works for you.
Do note, tho, most of the good ones are commercial
Can you open it in read-only? If you can, copy the data and save it in another file. Then delete the password-protected one and give the new one the name of the old one.
Hoping to help
kitty500cat