I have an old sony 5.1 surround sound player with the 5 speakers and subwoofer that plug into the back. I want a new dvd player tho, as this one isnt working so well anymore. Do I have to buy an entire new surround sound dvd player or is there a dvd player unit that my 5 speakers and subwoofer will plug into?

The speakers you have need an amplifier in order to provide a powered signal to them, such as that included in most receivers. So no, a DVD player by itself, even if it has 5.1 RCA audio outputs, isn't going to work.

It's possible that your current receiver has audio inputs for additional audio devices. However, if it was one of the really cheap "all-in-one" units, it may not have any inputs for 5.1 audio, either digital or analogue. If that's the case, you'll need a new receiver in order to take advantage of 5.1 surround sound.

However, I'd strongly suggest against getting another "all-in-one" Receiver with an integrated DVD player, for precisely the reason that you've just experienced: if the DVD part goes out, you'll be stuck with a receiver that doesn't allow many options.

Buy a separate home theater receiver and separate DVD player and hook them together with cables. You may be able to salvage the speakers, but speakers from all-in-one units usually are sub-par. If you're happy with the way they sound currently, you can keep them for now, but maybe upgrade them down the road.