My tulip bulbs have not made any flowers this spring, maybe due to lack of sun and/or phosphorus. Is there any chance they will make flowers next year if I give them phosphorus and more sun, or should I just throw them away?
It depends - do you have a more suitable location to move them to? In many landscapes, tulips (at least the hybrids) are a disposable item, as they get planted where they won't actually get enough sun to bloom again (or in more commercial landscapes, they bloom and are torn out to be replaced with other flowers for a continuous display).
Since they transplant poorly (IMPE) when growing, you are probably looking at two years from now if you have a spot to move them to, whether you transplant now and they are unhappy about it, or transplant after the foliage dies back for a less stressful move.
If that sounds like fun, go for it. You might aim for a three year program/rotation, where your sunny tulip field gets the bulbs that come out of the bed, they grow there for a couple years to restore themselves, and then you move them back to the bed. If it sounds tedious, either buy tulip bulbs every fall, or change to flowers that are a bit more cooperative about blooming most every year in the conditions you have.