No idea when HRTC will resume but private buses are already up & running from Delhi to Manali.
They are usually safe as many female travellers opt for them.
But since last two weeks few people have reported that these buses are only running from Delhi upto Baddi (Himachal border), then they were asked to board tempo traveler/ non ac bus for continuing journey until Manali.
Kindly be sure of that before booking.