VBA to unlock password protected sheet using cmd button

Hello happy campers!!

I have

Excel sheet, with 2 command buttons "Lock" & "Unlock"

Press cmd button1, this will password protect the sheet with password as "secret" (have this set up already)
Press cmd button 2, this will then produce a text box to require a user to put the specific password in to enable them to modify the sheet, otherwise it will stay locked.

Any advice would be very much appreciated!
galvinpaddy