Honesty is the best policy. While it's reasonable that you can't expect an employer to "price" you to include those years of experience that are now gone, any employer that treats you badly or as though you were smoking weed on your couch for those four years is an employer you do not want to work for in the first place. If you are as dedicated, honest, and hard-working as you say, you'll be a desirable hire regardless of your circumstances. Also, don't let this situation eat you up: I lost six years of development experience to infantry combat deployments that I could not avoid. That's not fair, but life's not fair. If you treat this like a challenge instead of a detriment, you will be a stronger and better person than the next guy (or gal). Chin up, and best of luck to you. :)