Worry about restoring macbook pro to factory settings

I want to restore my macbook pro to the default factory settings as it has become a bit slow over the years and I want to start fresh.

I have:
2011 Macbook Pro w/ Mavericks installed. (It originally came with Snow Leapard) and I want to install Yosemite on fresh install.

I have looked up how to restore the macbook however many of the comments say that after they input their Apple ID to install the operating system a message comes up with "This item is temporarily unavailable, try again later" and then they are stuck.

Is this a common problem as I've seen quite a lot from people come up with it.
Thanks

Back everything up on a external CD incase you have regrets. you can always upgrade again.
BUT
we are being scared into thinking we cannot operate our computers anymore.
what is worse that will happen?
slower internet?
personally for me 2011 was Apple's pinnacle, everything I owned worked flawlessly with plenty GB room to spare-pleanty of battery life and no spinning wheels. i honestly cannot not claim this with 2014 updates.

banesto said:

BUT
we are being scared into thinking we cannot operate our computers anymore.

Click to expand...

What pray tell lead you to that conclusion?

@OP Backing up everything is always a good idea. I don't think this is a common occurrence except right after the OS was released.

Slydude said:

What pray tell lead you to that conclusion?

@OP Backing up everything is always a good idea. I don't think this is a common occurrence except right after the OS was released.

Click to expand...

what i realized recently i have seen too many "afraid" and uncertainty about operating our computers including return to lion or and older more comfortable OS.
i would like to reming people we are smart, and can always control our computers and how we use them. we need to just start planting some much needed confidence in people's threads!