I am trying to install from scratch, with "command r", after erasing the hard drive Yosemite on an MacBook Air (13 inches, late 2010), but I can´t because it is "temporarily unavailable", it will be really temporary?, there is another way to do the installation?
MacBook Air
If the laptop is running extremely slow either you have a software issue or the hard drive is worn out or failing. You can check the health of the hard drive by running DriveDx and posting the report here using the "Additional Text" icon which looks like a piece of paper. If you are using a hard drive as opposed to an SSD, then any "Warning" or "Failing" notices from DriveDx indicates the hard drive is worn out or failing respectively and should be replaced with an SSD which will allow the laptop to run a bit faster than it did with a slow hard drive, but you do need to be careful with which SSD you use (Crucial MX500 series or an OWC Electra 3G SSD are most likely to be compatible), but only you can decide if it is worth investing any money into this laptop.
You can create a bootable macOS USB installer using the instructions in this Apple article:
https://support.apple.com/en-us/HT201372
Also here is what you should do when getting rid of an Apple computer. Keep in mind the instructions in this Apple article assume either you are using an SSD or you have Filevault enabled if you are using a hard drive in the laptop.
https://support.apple.com/en-us/HT201065
If the laptop is running extremely slow either you have a software issue or the hard drive is worn out or failing. You can check the health of the hard drive by running DriveDx and posting the report here using the "Additional Text" icon which looks like a piece of paper. If you are using a hard drive as opposed to an SSD, then any "Warning" or "Failing" notices from DriveDx indicates the hard drive is worn out or failing respectively and should be replaced with an SSD which will allow the laptop to run a bit faster than it did with a slow hard drive, but you do need to be careful with which SSD you use (Crucial MX500 series or an OWC Electra 3G SSD are most likely to be compatible), but only you can decide if it is worth investing any money into this laptop.
You can create a bootable macOS USB installer using the instructions in this Apple article:
https://support.apple.com/en-us/HT201372
Also here is what you should do when getting rid of an Apple computer. Keep in mind the instructions in this Apple article assume either you are using an SSD or you have Filevault enabled if you are using a hard drive in the laptop.
https://support.apple.com/en-us/HT201065
If your Mac has EFI Firmware Update 2.3 installed, here are some steps may help.
You may need to set the date to a time in 2017 and try it again. Once booted into Recovery Mode launch the Terminal app from the Utilities menu and enter the following command (press the "Return" key at the end of the line to execute the command):
date -u 0101223317
After setting the date to Jan. 1, 2017 with the time 22:33 quit the Terminal app and select "Install macOS".
If you have access to another Mac that can run macOS 10.11 to 10.13, then you can create a bootable macOS USB installer using the instructions in this Apple article:
https://support.apple.com/en-us/HT201372
Thanks very much, but sadly nothing works, had to restore it from a Carbon Copy backup.
The problem is that the Macbook became really slow, an I would like to give it away but guess does not have much juice left.
Install Yosemite in a MacBook Air (13-inch, late 2010)