You have not backed up the videos to any external hard drive or cloud storage, so there is no backup to restore from. You can try to use data recovery software to scan for the deleted videos on your iPhone, and this should be performed ASAP. The longer the time goes by, the higher the possibility the deleted videos will be overwritten with new files. Try any recommended data recovery assistant provided by Google or Safari and begin the data recovery task! Once you get them back, please make a backup to avoid further data loss!