Charlie Sheen Flip-Flops -- I'm Re-Joining Twitter

Charlie Sheen has had a major change of heart ... and has decided to re-open his Twitter account because "he misses his fans."

TMZ broke the story ... Sheen quit Twitter in July after 16 wild months because he just didn't feel like he was getting anything out of the Social Network anymore.

But now, sources close to the Warlock tell TMZ he just re-activated his account and plans to reach out to his 8 million followers ASAP because "He misses interacting with his fans ... and really wants to talk to them about important things in his life."

Among Charlie's list of important things -- we're told he's pretty fired up about an upcoming episode of 'Anger Management" which guest stars his famous father Martin Sheen.

We're told Charlie wants to try and keep his tweeting "professional" going forward ... but he's Charlie Sheen, so crazy isn't exactly off the table.