Iamhaigh s 6 d

I logged on today and it just wasn’t there. It’s not hidden. I’ve tried putting explorer into the task manager and it popped up for a couple seconds then disappeared again. When I rebooted it, It was there for a couple seconds and again, poofed. I scanned my computer for virus’s and nothing came up with that. Can someone tell me what to do? I’ve seen many of these kinds of questions with no answers that worked for me.