Law enforcement sources tell TMZ that police have closed their investigation into Scrappy's violent car wreck over the weekend -- which left him and a friend hospitalized and seriously injured. As we reported ... Scrappy says he doesn't remember the crash or the aftermath.

We're told cops didn't find any evidence of drugs or alcohol, and no other cars or witnesses were involved ... which led to their decision not to pursue criminal charges against the driver -- whom they believe was Scrappy.

What police did find, however, was nearby surveillance footage that captured the crash, which cops say shows Scrappy's car veering off the road, hitting a utility pole. Scrappy blamed it on exhaustion.

Here's the kicker ... although Scrappy won't be charged, sources say the case could be reopened if, God forbid, someone dies. Remember, Scrappy's friend, Ca$ino Roulette, was in ICU because his injuries were so serious.