1995 Dodge Avenger cranks but wont start

car was running then died in traffic.Had it towed to home.Thought maybe out of gas,so I put 5 gallons in.Still cranks but won't turn over. it's getting spark,screwdriver in plug wire saw it arc.Fuel is getting to the fuel injectors. I took off timing belt "inspection cover" and belt is a little chewed up but still intact. Could timing belt "jump" and is there away to adjust timing? How big a job is this?Approximate cost? We just bought the car and I noticed that someone cut a hole in the passenger side wheel well to access a bolt at the timing belt cover.Is this an adjusting bolt?

Thank you for any help