Sometime last year I hung out with this guy name dave I only know him by that name and only his cell number and I have been trying to find him through these other sites but they want to know every thing and that's all I know.:(

I'm sure there are literally millions of "Dave's" in this world.

Can you say "needle in a haystack"?

Unless you know someone else, who might know his last name, I believe this to be
A futile waste of your time.

Good Luck.

A needle in a haystack would be easy -- first and last name + age

You have a better chance of winning the Powerball Lottery -- Good Luck

Ok, where did you meet him at, did he mention where he was from, what school he went to, think of any details.

You might be able to track people with his last number, not sure of how to go about it without breaking some sort of privacy with the cell phone company, but I've heard it done before, good luck, I've been looking for someone for 23 years with only the first name with no luck yet.

You can get info on cell phone "owners" - depends on the cell phone company. Also depends on the reason for attempting to locate the person. You often need someone with a PI license.

(I'm an investigator in NY)