I was delete all files in my 951UI...

RouterOS Beginner Basics
1

I was upgrade my 951ui-2hnd from 6.40 to 6.41 and then i deleted all files in router… Now my 951ui become continually reset… I tried Netinstall but it cant see my router…
How can i fix this?

2

Netinstalling is the right way to go. https://wiki.mikrotik.com/wiki/Manual:Netinstall
You do need to set the ip on computer to a fixed ip in range.