The term "spreadsheet" is an old generic one.
Excel has workbooks which are AKA files.
Within each workbook can be multiple worksheets
Password to open the workbook?
Password to unprotect a worksheet under Tools>Protection?
Password to unprotect a workbook under Tools>Protection?
Internal passwords are easy to crack.
Passwords to open are more difficult.
See John McGimpsey's site for info on both.
http://www.mcgimpsey.com/excel/removepwords.html
Gord Dibben MS Excel MVP