I have accedently delete particion and i read thet this devace need special tool for backup
how can i restore particion
Since this is a Nexus device you can typically download the firmware from Google’s Developer Site as a “factory image” and reflash it following their directions. Factory Images for Nexus and Pixel Devices | Google Play services | Google Developers
See also, https://forums.androidcentral.com/google-nexus-7-2012-rooting-roms-hacks/191477-guide-nexus-7-factory-image-restore.html but read it very carefully as they cover all 4 Nexus 7 models (2012 wifi/GSM and 2013 wifi/LTE).