Start your mac holding down the "R" and Command keys. Hold them down until you get the apple on the screen. It will take a while as you will be stating in internet recovery mode.
Once it has booted, use disk utility to create a partition, close disk utility and choose restore from Time Machine (once you have attached your Time Machine Drive)
You can also choose to reinstall a fresh OS if you'd like.
crwdns2934105:0crwdne2934105:0
crwdns2934113:0crwdne2934113:0
crwdns2915270:0crwdne2915270:0
crwdns2889612:0crwdne2889612:0
1