Indoor cat getting out

So Hatchet is supposed to be a strictly indoor cat.

However one of the screens/windows in one of the rooms is broken and I am waiting to get it fixed,but it is hard to get in touch with my landlord...anyway Hatchet figured out how to get out through it.He never gets out when I am home...but when I go out,I always return to Hatchet outdoors.

He is supposed to be getting fixed at the end of this month and he DOES have tags on.Also my neighbourhood is pretty quiet with generally nice neighbours,except for a few odd ones.Actually one of the first nights I came home to find Hatchet gone and I couldn't find him anywhere.Turns out,one of my neighbours found him (he never had tags on then) and brought him in her house.But when she found out he was mine,she was relieved that he wasn't a stray or anything.

Anyway till I can get the window fixed,what should I do?
Should I nail the window shut? This was a suggestion from my family and it may very well work.

Oh I wanted to add...
Hatchet never tries getting out while I am here...so I think it has something to do with seperation.Because before he figured out the window,he would always meow and bawl when I was leaving.

My Tiger is always a good boy when I'm around, but if I leave the room or anything while the screen door's open he's out the dog door!

Maybe, if you don't want to nail the window shut, you could duct tape it or block it with something. I'd definitly do something just to make sure he can't get into to much trouble.

Yes, you could nail it shut or you could just tack up a piece of clear plastic against the window frame. Anything like that should stop him from getting out.

You can't let an unneutered cat out, ever. You must get him fixed right away, or lock him in a part of the house where he can't reach the window.

I agree with everyone's recommendations. I just wanted to also mention that he will still have hormones racing through his system for at least a month after he is neutered, during which time he could still impregnate a female. So please don't think that his strong desire to escape the house and mate will be shut off immediately after he is fixed.

I just want to echo what others have said. Block the window in whatever secure way you can. Be especially careful with an unneutered male, and like Robert said, it's important to be careful for a certain time afterward.
I'm glad your nice neighbor took him in so nothing bad happened to him. I hope he didn't run into any loose unspayed females.
One of my cats tries to get out so I have to be very careful, too. I had to retrain one of my dogs who was housetrained with a doggy door because I knew Molly would try to get out that way.

We have a nice big yard in a temperate climate... but of course, she finds lots of reasons to sneak in!