Lock cells in a row after input

I've been working in this worksheet and now I need some help building a VB code. As you can see in the attachments in several cells I have a working userform 'asking' for a password this password is linked to a cell in the spreadsheet.

What I wanna do now is when a user enters a correct case (same cases as used in userform 2 code, for example) all the cells before that one to lock. e.g. If a valid PIN number is entered in cell H4 cells G4, F4, D4, C4, B4 and A4 are locked, and so on for rest of the column.

Thanks in advance

Guys I really need some help here, somebody??