Ok, that is a problem …
Do you have an USB stick, and a system available you can download from ( household, neighbors, family, friends ) ?
Download “Farbar Recovery Scan Tool” from this topic https://forum.avast.com/index.php?topic=53253.0 and use the USB stick to copy it to your pc.
Follow the directions from that topic, and attach both FRST.tx and Additions.txt logs in your next reply.
Greetz, Red.