Hardrive problem pleasse help

Hello, i took my hardrive out and then put it back into my computer then it wont put by the harddrive it says please insert the pc disk or something so i done it and it goes to install put i cant select were to install it because it doesnt detect my harddrive iu have harddrive as first boot option, ive tried everything i duno what to do please help. and now i put all the boot options on hardrive and nothing comes up but it boots