No hdd detected when trying to install windows 7/8

Hello, ?here is the problem?A few days ago my computer went to sleep mode and wouldnt turn back on so i turned it off and on again. After the acer logo tho it said something like '' no bootable device. Please insert a bootable device and press any key'' Turned out that the hdd wasn't detected in the bios so i tried to see if it's connected properly but after realizing that i can't open my computer properly i gave up. Somehow the bios now detected the hdd tho everything was too slow. I tried installing windows again bu after 30 mins of defragmentation on disk C i gave up and shut it down. I havent been able to see any partitions in the installer since. The list disk command also doesnt show anything.?I've tried loading the correct sata drivers and switching from AHCI to IDE sata mode but had the same result.?Im using an Acer aspire 5755g. Please help and thanks in advance.