10+ year old domain was #1 for 5+ years but now nowhere to be found, what to do?

I have a 10 year old domain that was ranked #1 organically for 5+ years but now for this specific phrase our homepage doesnt come up at all but some of our pages do but we are like 6 pages back in Google.
In webmaster tools it doesnt say any foul play or banned etc. We still show up in the engines but again we are 6+ pages back but we show up in Local and PPC, what would you do for a site like this?
This domain doesnt expire either until like another 10 years.
It is on a couple year old…
10+ year old domain was #1 for 5+ years but now nowhere to be found, what to do?

See original post by tokipost