Problem from updating iPhone4s from 5.0 to 5.0

Recently I've updated my iPhone 4S from 5.0 to 5.0.1 but the personal hotspot is absent. There is absolutely no active switch within the system menu, attempt to place new APN in cellular data network, difficult to reset and several points. It is totally inactive.
Is there any solution on this problem? Thanks in advance for the advice.
