Please excuse my frankness, but allow your wife to give you a slow lubricated handjob as you are sitting down, fully relaxed. She should hold your testicles with the fingers of one hand while she strokes the length of your shaft with the other hand. Both of you then can see if your penis can become erect and hopefully ejaculate after a period of time. Practice this two to four times per week. If it doesn't work within a half-hour or so, come back to it the next day and try again.
How old are you?
Can you get erected with porn without problems?