Yosimite will not reinstal after disk erase

SO, my MacbookAir ran out of disk space (totally ran out) so i decided to erase my startupdisk in order to get all new free space, basically a brand new mac, then after all that happened, i went back to Reinstal iOS X Yosimite and it will not install, it does not give me an error message, the instalation will simply not progress, and the time remaning keeps increasing; example ( it goes from 8 hours and keeps increasing, whenever i went to work and came back at the end of the day it had gone alllllllll the way up to 235,798 hours, with no progression,) PLEASE HELP!