I accepted(but haven't signed contract) a job offer but I cannot go to anymore. Will I burn bridges with the company if I do this but I tell them I have a person that is a suitable replacement? Will this damage my reputation?
It depends on the reason you cannot go there anymore, whether you will burn bridges.
I wouldn't suggest another person as a suitable replacement, however, as it is a common scam in some parts of the world to do exactly as you describe in order to get someone in who simply doesn't know what they are doing, or worse.