The pull (recoil) start bearings are probably b*ggered, take it apart of have a friend look at it, it's a fairly simple job.
There's no need to drain the fuel, (double check it's a two stroke -- the exhaust will have a smallish tail hole and fat curvy expansion chamber(s)) estimate how much fuel is in it and pour in the measured amount, 5% oil should do it.
Ratios do vary greatly, do a search for the specified oil/fuel ratio for the specific quad.
As for not starting, it could be an electrical fault, do a complete diagnosis, or have a buddy take a look at it.
Do some online searching as for what to check for, doesn't have to be four/two stroke relevant, just start with the basics, fuel, spark, fuel air mix etc etc.
Hope this is of some help.