I was building one of the starter circuit builds and saw that my circuit wasn't working. I figured that I used the Temp Sensor on accident but I didn't. When I inspected the transistor, I noticed my transistor wasn't the one that the Vilros Ultimate Stater Kit Guide had in it.
Long story short, I have a P2N2 222A F19 Transistor and I need a P2N2 222A A18 Transistor. I couldn't find any online to purchase. Does anyone know where I can buy one? Thank you in advance 
The F19 and A18 read like date codes. They are probably the same transistor type.
RogelioIIT:
Long story short, I have a P2N2 222A F19 Transistor and I need a P2N2 222A A18 Transistor. I couldn't find any online to purchase. Does anyone know where I can buy one? Thank you in advance
Searcj eBay for 2N2222 and you can find lots of offers.
This transistor type is sold in different types of packages, so if package type does matter for your application, watch out to order suitable package type (i.e. TO-92 package)
Perhaps also read Wikipedia 2N2222 - Wikipedia
Sounds like you have 2N2222 transistors manufactured by On Semiconductor. http://www.onsemi.com/pub_link/Collateral/P2N2222A-D.PDF
These have the part number in three lines on the package:
P2N2
222A
xxx
where the xxx indicates the facility and data at which it was manufactured.
So you do have the correct transistor - it just wasn't made in the same week at the same factory as the one your're comparing it to. The problem with your project must be something else.