Steam doesnt update/doesnt open at all.

Basicly, Yesturday i wanted to speak with my friends about something important.
When I opened steam, it would not open at all. (Note, it did NOT say updating steam at this point, it just didn't appear.) So i try closing the steam process, restarted the computer and it still wouldn't work. So today I had a different problem when I tried opening steam. It just started updating, stopped at 0%, and the updating steam disappeared. (No, steam did NOT open then.)

If anyone could hurry, I would really appreciate it if you could help me. I cannot afford to reinstall steam right now. Otherwise, if it REALLY does involve reinstalling, then i guess i have to. This has happened before, although i had to reinstall. If there is any other way of fixing it, please tell me.