My friend keeps puttin herself down, by saying things like I can't do anything right, and I'm a looser... what do I do, I'm trying my best she just got dumped

Get her out in the world, hang out, see movies, get your other mates together and just help her enjoy life. Being dumped is hard for people, but she will find her feet eventually. Listening to music is a great soul healer. Find a book that she might enjoy, just let her know you are there for her. Its good of you to be concerned for a friend =)

Be a support to her. When she says these things, tell her otherwise. Make her feel special, and let her know that you will be there for her and you don't think the same way that she thinks about herself.

There are great suggestions on how to heal after a breakup in the relationship thread.. read the stickies.

Its good that your supporting your friend and I agree with the above suggestions,I also suggest that she post her question and get some feedback,if only just to vent?

If you think it would help her.