Cry Cant log on!!!

Question

Last night, my network wasnt working correctly and so I clicked on some network thing and I think it changed my domain, bc now I can't log into my laptop at all. Is there anyway I can do a system restore to go back to my old settings or is there any way I can get past that first screen to change my settings back to normal? PLease help me I have several papers due when I go back to school..