New Sheet Add, Sheet visible & Menu disable problem

Hi,
Problem I: I've a excel file with multiple sheet & VBA coding. In coding has some sheet locking- unlocking code. Here has some code to set page visibility. When I'm trying to change page visibility then getting problem. My sheet visibility is now veryhide and I'm trying to set visible (-1 enum value), but it's not allow me to set it. Now I can lock-unlock the sheet (codes are executing).

Problem II: When I'm going to Menu -> Insert -> Worksheet then it's disable, and when I'm right clicking on sheet then Copy, Insert, Delete popup option is disable. I need to enable these.

Problem III: To solve problem II I've tried to write some code to enable Worksheet menu. This code is;

CommandBars("Insert").Controls("Worksheet").Enabled = True

But this code is working fine for File, Edit, etc menu & sub-menu but not for Worksheet.

My file is password protected and I'm giving password correctly. Seems to me for that file has some settings, which I don't know. If any one know solution then please help me.

Thanks in advanced,
Suman