hey, i put slime in my bike tires a few months back, but for some reason, the slime backed up and blocked up my valve so i cant put air in my tires. how can i fix this?

Take slime tube out, throw it away. Put regular tube in.

1. 2. Don't put slime in again!

You could probably swap the valve core from an old tube.

i used the slime cap to take out the core and that sucked out the slime

Sometimes little shreds of rubber in Slime get into the valve in strange ways that keep them from sealing or from allowing air in. I would guess your tubes have Schrader rather than Presta valves. When I have had these problems I introduce a few drops of water into the valve and work it back and forth. That usually clears the blockage. On Schrader valves I remove the core and use a Q-tip to swab the upper part of the stem.

I have had a love-hate relationship with Slime. After learning to use a few drops of water to clear the valve area, it has been mostly a "love" relationship. We have more than our share of goat's head thorns where I live. Tire liners stopped most, but not all of the goat's heads. But, they also destroyed several tires and tubes. I have removed them and am depending on Slime alone. I would advise not to give up on Slime yet.