Help me play people who put on spin

I play alot and i lose quite alot of points when people put a heavy amount of topspin on the ball. how do i get better?

Probably, you are not hitting "up" enough on the ball to reverse heavy topspin so that the ball rolls over for you on the way back. Result? Your shot has no topsin on it. Or, very little topspin but not enough to keep your shot from going out.

There are several approaches. One thing you can do is learn to hit with more topspin yourself.

Another thing you can do is to position farther back, hitting the ball on the descent of its bounce, when it's easier to impart topspin to it. (There are disadvantages to doing this, however.)

Yet another thing you can do is just work with the spin you're getting. Watch your shots. If they are coming off your racket flat or with underspin, then play them as flat or underspin shots. This means that you have to aim lower. You might as well hit the ball on the rise if you can then.

I fully agree with Kathyk comments.
Just adding a few things. Despite a ball with topspin looses less speed after the bounce, I advice you to try to hit it on the rise. Think you'll need less power and focus on control. Doing so you give you opponent less time to adjust their topspin hits.
Players with a lot of topspin usually move very well left and right and pretty badly back and forward or high and low but will find more angle than you can.
They hardly rush to the net and wait for your mistakes.
Emphasis on control rather than power and feed them with a great diversity of balls (high & slightly across the court, short slices straight or far from from them in serve's square diagonal, and always kept low).
Break their routine, whatever it takes too (use dropshots, volleys foolowing a delayed rush to the net - sorry my english is not good enough to describe clearly all technical tactics -).
You've got to choose between beating them at their own game (more topspin skills required then, bad luck if you play Nadal ;oP) or tactically with what you have.
In the second case, watch and leran from winning matches of Mc Enroe / Bjorg-Lendl, french player Santoro and all matches of Edberg towards is final with Chang in the French Open, or from those rare guys who get rid of Nadal.
In any case, as these players don't give many points, get ready psychologically for a long and intense match.
Good luck.

Thanks for that