How to make a ntfs partition on internal HDD read-only, and later writable?
Solution 1:
Right click on the partition and click properties - in the security tab change the permissions as appropriate. Maybe add 'everyone' and give read access only where as your actual login (and the administrator) remain on Full Control.
EDIT
Or, if all files and folders can live under one top root folder you can mark that as read-only and ensure this is applied to sub-directories although be-careful software can over-write read-only files!