Macbook Pro stuck after introducing password

I have a Macbook Pro 13'' Early 2011 and originally came with Snow Leopard OS. About 2 months ago I updated its OS to El Capitan and worked perfectly. Yesterday, suddenly after turning on the laptop and introducing my password it just gets stuck with the "loading" circle. I have tried without success resetting NVRAM, safety mode, and letting it run out of battery. I also tried reinstalling my MacOS by using Command+R but when I get to the point of beginning the installation it asks me my Apple ID which I introduce correctly and then always shows the message "This item is temporary unavailable. Try again later". Has anyone had the same problem and help me fix it please?! Thanks!