If there's no window and no other source of natural light, then according to the MLS rules it's a 1Br with a den. That will impact market value if you are competing with other legal 2 Br's. I often see such units marketed as 2Br's but when compared with true 2 Br's they often loose out due to potential resale issues. As Michael says, it's all down to price which ultimately shows you that if it's priced right a buyer may not care if there's not a window. However, "priced right" means dropping your price until someone is prepared to buy. That's where it will affect your resale value.
Good luck, Ken.
Getting past that....how will your "2nd bedroom" be effected if it does not have a window? Depends on the buyer. If it is somebody looking to use the 2nd bedroom as an office they may not mind. If it is someone looking to have a roomate it will depend on the roomate. There will be some people who will be turned off and some who won't.
I guess my question is this: Can you add a window? If its a highrise I'm guessing no so there is not much you can do about it. Just realize that some people may not like it but as long as your are priced right you shouldn't worry about what you can't fix.
Hope that helped....good luck!!