reinstalling macos

I am currently having issues with my MacBook Air (around 2015) installing macOS Sierra. After I went into recovery mode, I may have accidentally erased something I shouldn't have and cannot install macOS after trying two times and error message popping up after installing. I don't know what to do from here as there is no startup disk available when I try to restart the laptop. Ive also tried going into disk utilities but nothing something seems to be working.