Hello Hadi1983,
In situations where the download takes longer than 15 minutes, you'll want to wait for the download to complete before reattempting the process per the details below:
If the download takes more than 15 minutes and your device exits the recovery mode screen, let the download finish, then repeat step 3.
You can also find that information and steps in this resource: If you can't update or restore your iPhone or iPod touch - Apple Support That process is also applicable when attempting to update or restore an iPad using a computer.
If you have any further questions, don't hesitate to let us know.
Take care.