My Pfitzer juniper is about 30 yrs old. It is very large and lives by my back fence. The front is healthy but the back part by the fence has died. I would like to know if I can cut it back to one foot above the ground and have it grow back.
All junipers have a dead zone in the middle due to insufficient light. This may be the problem with the part of your juniper that is against the fence. This area will not grow back unless you see some green growth in there.
For any juniper severe pruning is not recommended. It is suggested by the Morton Arboretum in Illinois that you should not cut down a juniper by more than 20 percent. What you could try is reducing your shrub by 20 percent each year but remember that the dead zone might be truly dead and that will not grow back.
If you do cut your shrub down to the ground it will not grow back, but will give you room to plant a new shrub that may be more compatible to your garden in terms of size.
The following article provides additional information on pruning of evergreens: https://www.mortonarb.org/trees-plants/tree-and-plant-advice/horticulture-care/pruning-evergreens