Is there anyway to use this without the knob, or do I have to buy a new one? Thanks in advance

Your cast control knob on the handle side? You will backlash a lot if you don't replace it. I think pitches and short cast are okay but don't try to bomb it.

And if your not good at feathering the spool then don't do it

Ok cool, thanks kcdinkerz. I hate those birds nests! 

Lots of those knobs are the same size, lots of different brand reels tension knobs are universal so u may have an old clunker reel wich its knob may fit it..

You need a new spool tension knob (plus spacers, shims, spring etc). I hope you haven't managed to lose the bearing in there (if there was one). Check the schematics and order the parts.

Call the manufacturer and ask for a replacement. There may be no charge.