1995 kx125 oil?

uh.....

How are you looking in the crankcase? You pretty much have to pull the cylinder off to see that. Regardless, there is no crankcase oil since it's a 2 stroke. The crankcase is lubricated by the fuel mixture. Hopefully you are putting 2 stroke oil in the gas? A non starting condition is lacking one or more of the following things. Fuel, compression, spark.

If you are asking about transmission oil, you will get many different opinions as to what oil and how much. I would recommend a service manual and follow their recommendation. In the mean time, use a 10w 40 motor oil WITHOUT friction modifiers such as Rotella or similar. ATF Type F works great too. A motorcycle specific gearcase oil specified as safe for wet clutches would be ideal as well. Drain it and put in most of a quart when you refill. About 700ml should do. The correct amount of proper oil in the transmission will probably help your shifting problems. Get a service manual ASAP.

The crankcase I believe is oiled by the oil in the gas. The gear case needs oil in it. Where are you looking to see any oil? The bike should have a way to check the oil. Even if it has oil in it I would change it anyway, just to know it was fresh.
About not starting, all you need is spark and an air-gas-oil mixture and it should start up. Check the plug to make sure it has good spark, if so, then go on the fuel-air mix. When it gets to that, someone more knowledgeable will need to go there for ya. Theres plenty of helpful people here. I have made some posts and have had several people help me.
Good luck !