No entry sign means it can't find an OS. Judging by the picture I imagine you have a 13" 2012 MBP (or a slightly earlier year)? If so, likely the HDD or the HDD cable has failed (or both).
Best to take it to an Apple Store, they should be able to sort out the HDD cable for you. While you're there, it would be worth upgrading the HDD to an SSD to improve performance & longevity.