HELLL!!!MY HAIR LOOKS CLUMPY!!! HELP GUYYS!!! ANY HAIR PRODUCTS?!?

I have layered hair an inch past my shoulders its layered! and I have it rebonded but i really have straight hair.. the rebond does not have any effect :P my hair is still unmanageable. so here's my problem. when i straighten or flat iron it ,it looks clumpy like the hair or strands is grouped if you know what i mean. i use brush btw... any hair products? thankssssssssssss!