It was blowing cold air, but now not. Not sure why?

If the pressures are too high, there very well may be a restriction in the system. Air conditioning repairs absolutely require professional, skilled, experienced diagnosis and repair work, I'm sorry to say. It is a complicated system and has too many complexities to try and coach or educate in a forum like this. Especially essential is that only licensed technicians -- that have taken the EPA's section 609 certification test for handling refrigerants -- should work with refrigerants. This kind of eliminates most folks from being legally permitted to work with refrigerants in the first place.