Typically, the nonce starts a 0 and it is incremented until a qualifying hash is found or all the possible nonces have been tried. If all the nonces have been tried, then something else in the header is changed and the nonce starts back at 0. This process keeps going until a block header that has a qualifying hash is found.
Alright, from your statement you said if all nonces have been tried .. does this means they have a specific range value or a max value??