How do i find my correct laptop charger!?

Usually the adapter type required is printed on the bottom of the laptop. The information is also on the Toshiba website.
Once you have the correct model figure, type it into ebay and find one for a good charge.
Also be careful with universals as these mostly overpower the components and give your machine a shorter energy span.
If I were you I would wait until I had the precisely one.

Update:

Jamesmic.. is flawed. The voltage must not be difficult than hunted and the amps within 10% tolerance.
I believe yours is 19volts and 3.42 Amps. Don't go higher As it will slowly burn out the components.