I would have to go with the common thing....
Make it look like Triple H hurt himself. Have someone just beat the crap out of him or say that he injured him self in a match. Keep him off TV for a month or two. Just let him do backstage stuff as usual. Then turn a heel champ....Preferably Edge...
....then have there be a battle royal or something or just have him challenge any one in the back. Trips enters and BOOM because he was gone all that time...Instant Face. Worked last time for him.
Just have Cena beat the crap out of someone people respect. Or have him swerve someone. Like maybe a tag match with JBL and Eddie G Vs Rey and Cena. During the match Cena turns on Rey and joines sides with JBL and boom. Then they would have to have him change his whole image into a person like JBL so that the rapper thing isnt catchy anymore.
Those might of already been said. I didnt really have enough time to read because I have to go.....