I have had this happen to me in the past, and what i did was just put him back into the tank and hoped for the best. That being said you need to secure your tank so he cant escape again (I once had 1 escape, then re-escape 10 minutes later while I was trying to find my glass top.) I would also check your water quality, im not sure if this is relevant but when mine escaped it was when I hadent changed the peet for awhile and the pH was neutral to hard. Also if you notice any cuts or scrapes on him you might want to try adding Mela-Fix, its an anti bacterial and will help speed up the healing of wounds.