14 Year Old Son + Windows 8 = Unusable laptop...everything is wrong

Hi all, really hoping someone can help me out here!

My son has an Asus laptop which he has managed to completely screw up from dowloading various streaming links I suspect.

I cannot open any browser without popups coming from every angle, every page takes forever to load having opened several others.

I have tried restoring to a previous restore point - errors out
I have tried doing a full refresh - errors out
I have tried reinstalling windows - errors out - gets to 'configuring windows upate' then 'a required drive partition is missing'

...and it won't recognise USB sticks either

I started to go through the list of cleans-ups on the stickies but it was taking 10 minutes just to get to a stable internet page!

Am happy to do a complete re-install if someone can advise how I can get to that stage?

Thanks in advance.

 

Thanks, am trying to work through that now, but the time it takes is killing me...its taken 15 minutes to get to the MS page to check which BIT version I have...