I have a train of hydrangeas that have spread from one down the line. They've always been the pride of my garden. In the past 30+ years they've been here (Upton, MA) the deer have nibbled at them during the winter. This year however, they've completely denuded the lower branches of the tallest and have totally stripped the smaller plants. I don't know what to do to save them. Some people have told me to cut the bushes down to 1 or 2 feet from the ground and fertilize them throughout the spring and summer? Can they be saved. Not only were they beautiful, but also have sentimental value.
You could do the rejuvenation pruning and cut them to the ground. If those hydrangeas bloom on old wood, you won't get blooms this year. Skip the fertilizer so they can recover. Hydrangeas need little to no fertilizer.
https://www.gardeningknowhow.com/ornamental/shrubs/shgen/rejuvenation-pruning-tips.htm
I bought a hydrangea plant at the supermarket I want to grow it indoors by a window will it last or will it die quick
You can grow them indoors. This article tells you how:
https://www.gardeningknowhow.com/ornamental/shrubs/hydrangea/potted-hydrangea-houseplant.htm
Maybe. Some formulations of Miracle Gro contain excessive levels of nitrogen. A better choice may be any general purpose, slow release fertilizer with a NPK ratio of around 10-10-10. Holly-tone is fine but apply it by your average date of last frost at full strength and then again, at half strength, 3 months before your average date is first frost.