Hey There,
I recently purchased a 2.8 inch tft display screen for my arduino projects.
When using the graphicstest file in the examples and uploading it onto my arduino uno, I was met with a surprise. :-\
There was a multi-colored grey and pink screen taking up 75% of the display, it sort of looked like a tv grain. Whatever came in contact with it (like the duplicating lines from the example) would duplicate there and stay there even after a reset until the usb cable was unplugged from the computer. 
I don't know what to do, any suggestions? 
Please post link to your display. e.g. Ebay sale (or photo of pcb side of shield)
Which library.
Which version.
Which example.
David.
You have a regular "Blue 2.8 inch" Mcufriend style shield.
Leave the Arduino IDE.
Remove any library folders that have come with the accompanying ZIP.
Start the IDE. Make sure that it is reasonably current. i.e. v1.8.x
Run Library Manager from the Sketches Menu.
Install Adafruit_GFX and MCUFRIEND_kbv libraries.
Run the examples from MCUFRIEND_kbv e.g. graphictest_kbv and diagnose_TFT_support
Ask if you have any problems.
The general advice is: Use Boards Manager and Library Manager from the IDE. Do not trust ZIP files from unknown sources. (the ZIP from JayCar has libraries hacked from obsolete versions)
David.