There might be room enough to tilt the top rail and unsnap them with the window trim in place, there are a number of different methods of hanging them. It is a DIY job! First one I had break I took it down and took it to a blinds shop to get repaired, they wouldn't touch it! I bought the proper nylon string and did it myself in 20 minutes. Lot's of resources on the interwebs:
Blind & Shade Repair | Instructional Videos | Printable Instructions | FixMyBlinds.com
To find the size of the string, rap it tightly around a pencil 10 times, measure the length of the coil and divide by 10. Nylon cord (string) is available at some larger sewing/fabric centers, etc. The 'repair kits' are over-priced. I ended up buying a spool of string (3,000 ft!!) on Ebay for $12.