God knows your situation and doesn't blame you because you can't do everything you once did, including going to church. I've faced a similar situation as I have grown older.
Do you remember King David in the Old Testament? He wasn't perfect -- but he sincerely sought God most of his life, and the Bible says he took delight in worshipping with other people: "I rejoiced with those who said to me, 'Let us go to the house of the Lord'" (Psalm 122:1). But when David grew old, he was no longer able to take care of himself or move about as he once did (see 1 Kings 1:1-4). God didn't blame him for this, however -- and He doesn't blame you.
At the same time, do all you can to maintain contact with your church. Let your pastor know of your difficulties, and encourage him and others from your church to visit you. Keep in touch with your friends also; loneliness is a common problem for older people, and you should do everything you can to counteract it.
In addition, make this a time of spiritual service and growth. You can't do everything you once did, but you can pray, and you can encourage others with phone calls or notes. Most of all, keep your eyes on Christ, and on "the hope that is stored up for you in heaven ... where Christ is seated at the right hand of God" (Colossians 1:5; 3:1).