Vinyl windows need little maintenance, apart from washing to keep them clean. Hinges may sometimes need lubricating, and occasionally you might need to replace a catch.

Broken catch
Pry off the fixing cover with a screwdriver then remove and replace the catch.
The screw is often covered

Stiff friction hinges
Lubricate metal hinges with low-viscosity oil. Spray plastic hinges with polish containing silicone.

Cleaning vinyl
With warm water, remove as much dirt as possible. Use a mild detergent on stubborn marks, then rinse well, especially the seals. Some cream cleaners can be used on vinyl, but keep them off the seals and rinse very thoroughly. Some cleaners are only suitable for smooth, white vinyl, not wood-grain effect types. Never use an abrasive cleaner on vinyl.