Orkut is blocked by the Indian Government so I couldn't (or can't) able open my Orkut profile.
1) Please remember to capitalise the word "I".
2) You need the article before the name of a government.
3) Whether you use couldn't or can't depends on when you are talking about. If it's an existing problem, then use can't. If you are telling someone that, for example, you tried to log in to Orkut yesterday, or last week, and you were unsuccessful, then use couldn't.
4) Orkut is presumably a brand name, or the title of a website. If so, it requires a capital "O" as it is a proper noun.