Stephen says Mel packed up 10 boxes of his belongings, which he picked up on Oct. 4 -- but he was shocked at what was NOT in the boxes. He says he was expecting to see his personal baby pics, clothes, shoes and paperwork.

Instead, he says all he got were Mel's old clothes, some crappy used towels and his step daughter Angel's clothes. Stephen thinks Mel trashed his stuff in retaliation. He's filed docs asking the judge to let him go on a search and recover mission.

Remember, Mel has a restraining order against Stephen -- but he's requesting a 2-3 hour reprieve, so he can go into the house and get his stuff.