If you are in immediate need of a mortgage and your scores are well below current underwriting guidelines, you may have to seek a 'hard money' loan that typically requires in the area of 50% down. They are short term only, usually maxing at 18-24 months, and are not cheap.
Fixing the score is your best bet.
I work with lenders that go as low as a 580 score. Give me a call or send me an email to discuss your situation.
Smart Mortgage Centers