Charlie Sheen, (Two and a Half) Man at Work

Troubled thesp back on the set of his hit CBS sitcom after production shut down to accommodate his rehab

Two and a Half Men is back to full capacity.

Charlie Sheen returned to the set of his hit CBS sitcom this morning and production resumed after being shut down for the last three weeks to accommodate his stint in rehab, according to a rep for Warner Bros. Television.

There are four episodes left to shoot for this season. The network has insisted the work stoppage wouldn't be noticed by viewers, because the 44-year-old actor timed his treatment to coincide with a planned two-week hiatus, thus delaying shooting by only a week.

Sheen sought what his publicist, Stan Rosenfield, said was voluntary in-patient treatment at an undisclosed facility as a "preventive measure" to deal with his personal issues.

The newly sober Sheen was all smiles yesterday when he turned up at an Aspen courthouse to plead not guilty to domestic violence charges resulting from the  Christmas Day row with wife Brooke Mueller.

If convicted, he could face up to five years in state prison. However, Aspen District Attorney Arnold Mordkin said he hasn't ruled out a plea bargain in advance of the July 21 trial.