a desk top PC?, what is it? use full names of things.
you never said what the screed did, is it black all the time.
if yes, does BIOS screens work?
F11 key, (the magic key) on older HP its F10 older still (none)
what year PC is this, full model number , type it out full off the service tag.... i cant guess omni this is. there are 29 models and subs.
The newer HP systems, all have this F11 key
this is the magic key as you boot, you hit it fast (tap tap tap)
and it goes in to recover mode. My 2006 Laptop does.
the HDD if still working and corrupted,
will run the virtual installer disk, via a hidden partition on said HDD>
if that is confusing, try to imagine 3 ways to install.
HP recover disk called the media kit. (uses on replace HDD )
MS disks, wrong, and will fail., ask how if must,,,,
if you and gone to HP forum or the support page
you'd have seen there is may different omin100s, lots
sorry cant guess yours...
you asked for help and cant muster up the service tag words
full model at least.
if you had id have pointed to the page that tells you what to do step by step, at HP.com
even what to do when it dont boot,all ways from SUNDAY.
the oldest one supported is 2010 year.
here is 100-5000 omni ,series, many in series.
no start actual pages... i see it covers most ways, (weak on hardware causes, there are vast cause under that topic, ask)