When you need a new power cord it is important to get the right one. Sometimes you can just search amazon for the make and model, and sometimes you need to be more specific.
You need to first make sure you are getting the right watt size. To get this you take the volts x amps. e.g. 19v times 4.74 amps = 90 Watts
If that is like your adapter I would search 90 Watt Toshiba Satellite S75 adapter.
Make sure you read the reviews and get a highly rated adapter.