Ever since a 15month deployment to iraq my energy levels have been non exsistent gained 50lbs in 3months. My sex drive is down and I have no drive.?

Probably depression. Are you reliving some iraq experiences in daytime flashbacks or nightmares? Have you isolated yourself from the outside? Are there family issues plaguing you? Are you irritable a great deal of the time? Clearly your energy, sex drive & control of eating are poor. Are you having trouble fitting in to family and society? It may be depression & some ptsd. Get professional help asap. The va can help.
Physical. I would get a full physical, also check thyroid as well as testosterone, blood count, kidney, liver, and electrolytes. For sure explore depression issues with doctor, but look for other causes.
Low sex drive. The most important and immediate answer is by asking a physician to perform a testosterone level. Many things can affect sex drive including taking some medicaitons. However testosterone will tell you if you have impairment. If you are a woman medications, stress and lack of intimacy will impaired your sexual drive. Man often fail to note the importance of verbal communication.