Help with a projectiles lab

I'm an AP physics student, and today I think I messed up. We did a lab in which we launched a marble at a known angle and recorded the distance it travelled in order to calculate the initial velocity. I performed the lab, got all my data, and realized that the launcher for the marble was being released from 17cm above the surface it landed on. Basically, what I'm asking for is a way to calculate initial velocity from horizontal displacement, angle of launch, and with a net vertical displacement of -17cm. For the lab we were NOT allowed to record time, so this value is not available for the calculations. Sorry to bore you all with a simple mechanics problem, but I'm in desperate need of help. Thanks in advance.