Is their any way I could curl my hair without using heat ?
Sleep in a roll bun?
On YouTube you can find where people have don't it using pencils or something like that... You wait till you hair is damp and then roll you hair up in a pencil and blow-dry it.. Then take it out! Probably want to use hairspray
You can use rollers in your hair and sleep in them or to get a wavey effect to your hair you can braid your hair in different sections and sleep in them its a bit more comfortable then the rollers.
Sock curls look it up on YouTube