Are film SLR camera lenses universal?

Basically I broke the lens on the Pentax p5 I have, and i was wondering if all the lenses for pentax (that are usually put onto the digital slr's) will fit onto mine?
and do they make like, adaptors? (because all my other lenses are nikon) So that i could put my nikon lenses to my pentax?

Added (1). And is it worth it just buying a new camera because i only paid like £10 for it in a charity shop?

All Pentax k-mount variations will fit but look for earlier non-AF lens types for the most compatibility. Check your manual for a compatibility chart.

Nikon lenses? Even if you can find an adapter (and do not try to mount them without an adapter, they may go on if you push a bit but the lens will only come off using a jeweler's saw!) function will be limited. This may be a good time to look for a Nikon film body like an FM-2 and sell off your orphan Pentax to someone looking for a backup body. Cheapest good Nikon body would be an EM for your application, if your Nikkor's are newer AF or AF-s or G types look for an N80 range body. The body will probably cost less than a Pentax to Nikon adapter.

Your P5 will only accept lenses with a Pentax K-mount. Aside from Pentax, you can use Tamron, Sigma, Voigtlander, Zeiss, Tokina, Promaster or any other brand as long as it is K-mount and for full-frame dSLRs or film SLRs. You can use other lens mounts only with an adapter but any auto functions will be lost. I'm not sure if there's a Nikon lens to Pentax adaptor.

As a side note, it is possible to mount a Nikon lens to a Pentax body. The index point will not be centered and the lens will barely be hanging on but if you can focus (doesn't do infinity) and set the aperture manually, you can take a shot. Just be very careful. The lens can drop anytime. Not really recommended away from the soft confines of a bed.

The P5 camera itself is great. It's one of the sturdiest camera's Pentax built. If it's in good condition, keep it. If you can find a Pentax-A 50mm even if it's just f/2, grab it. That would make a splendid combination.