Callback

What would you tell yourself if you could call yourself in the past?

Main character lives normal life (for closeted gay guy), grows up, eventually discovers quantum effect to detect and interact with particles through time, but only on molecular level. Works out way to affect current in wires and devises phone that calls itself through time. Calls self and suddenly remembers receiving call. Everything he says changes history instantly and he hangs up to ponder, before attempting to change his fortune, with disastrous effects. He's just barely able to reset everything before the changes are irrevocable (i.e. preventing him from inventing the device and thus changing history to correct the mistake; the "call" would have become an unexplicible event). He does manage to arrange to get a boyfriend and make suitable investments, however, before locking the device away never to be used again.