You should contact dealers of house trailers and ask them where to buy windows. You will need the brand and model of your trailer when you call them. The windows are probably made from Plexiglas. If you only need the glass replaced, you can probably call a glass company near you and they should be able to custom make it and install it. Look in your local yellow pages under “glass replacement”.

Lowe’s don’t install anything.They have a list of contractors that do it. Any handyman can replace a window. You probably won’t be able to get the exact size as the old, but close enough.