Can anyone help me with iCloud and back-up problems with my iPhone 4S?

My iPhone 4S will no longer back-up to iCloud. It says I have 0 storage, so i tried to purchase more. It will not accept my Apple password, so i cannot get my phone to turn on "back-up". I have a million app updates I cannot download, too. I've tried all the steps listed online and nothing works. Sorry, I cannot tell what iOS my phone is currently operating (or not operating) under. Can anyone help?