Hi there, and welcome to the forum!
If I understand this correctly, you're trying to make sure that everyone's info is in the same file, but you want each employee to provide a password when they open the workbook that only allows them to see their own sheet?
This could be done with VBA, yes. There's a BIG caveat to this though... If you users in your organization who are skilled with VBA, they could easily break any protection that VBA could offer.
The better solution might be to actually create separate files for each user, then have a macro to consolidate them into a global report for your own purposes.