The above suggestion for a multi-step vinyl window polish is right on. The key thing to keep in mind to prevent fogged/scratched up windows again in the future is to NEVER use paper towels on vinyl windows. Paper towels are made from pulverized wood products which impart millions of scratches over repeated uses which will eventually fog them completely, ultimately causing them to turn yellow from the sun being blocked by the scratches and heating them.
Instead, use a slightly moistened soft cotton towel, old tshirt, etc. with lots of water with a bit of detergent added. Or a microfiber cloth which works no better than cotton where this job is concerned. Just make sure paper towels are never used on them again.