When i washed my hands to check the strings on my iud i may have dried my hands with a towel that had semen on it. what are the chances of pregnancy?

Unlikely: Sperm require warmth and moisture to remain viable but are short lived when exposed to drying, as would occur on a towel. Some estimates suggest 20-60 minutes. Also, how many can be adhered to your finger if you rubbed and dried it on a towel? Your IUD is intended to protect you from the millions of sperm that may be introduced vaginally during ejaculation.