my phone keeps restarting(sony ericsson arc)

[Don Redmond]

i left my phone at a friends place and when i got my phone back it had super user on it also pimp my rom now the phone will not start up at all it starts to boot up but then restarts never turning on .there is no way to fix it with pc companion and i dont know what to do is there a way to re-install a new os myself or any thing to help thanks