I started typing in finder the wrong letter now I can't navigate to a file. How to start from beginning? The finder jumps to file starting which the letter I typed. I typed Z, now I want to see files start with Y. If I type Y it will search for ZY but I want to start from the beginning. 

How does the system reset search?
As nohillside said, you can just wait a couple seconds for the buffer to reset, but you can also hit escape to clear it.