Ok. Like previously mentioned, at which step in the support article I linked to is the process failing?
In order to help you we need more details.
From the information your provided, I am not sure Which state your watch is in. Is it completely resetted and unusable or still usable but just not connecting to your phone?
If the latter, please let us know which, if any, of these icons may be showing on your Watch.
Status icons and symbols on Apple Watch - Apple Support
And before re-attempting pairing you may have to make sure it is completely unpaired.