Hi, im trying to fix a Aspire V5-571P-6499 laptop, its problem is when i power it up it shows Acer logo then goes to black screen with "operating system not found" in top left corner, iv turned off then turned it on ctrl+alt del and then i hit F2 n got into Bios, can i fix this problem without losing my data? any and/or all help would be appreciated,Thanks,