newbie bigtime

hello from ARIZONIA im really new at this and need major help with my gas bike

im having trouble with my bike and the person who chose to take it apart .... i got my shoe lace caught on the clutch cable and pulled the screw and keeper off the end and thats where my trouble started then my clutch was taken apart and messed with and now my chain has been taken off .. but the real problem is if i put the baffel in my excust it is like it is starving for air and if i put it in it might start and go 20 mph how do i fix it not having the go it had a month ago it went 35 mph now im lucky if it goes 20mph