If a player recovers a fumble by laying on it knees on the ground is the play dead or can he still run the ball?

The rules concerning when a player is 'down' are different between College Football and the NFL. In the NFL, a player must be 'down by contact' for the play to end, therefore, if he were to recover a fumble while on his knees he would be able to get up and run with it as long as a member of the opposing team did not touch him while his knee(s) were on the ground. There is no 'down by contact' rule in college football. Once a player in possession of the ball has a knee (or elbow) touch the ground the play is over. The player would not be allowed to get up and run in college ball.