A turkey breast can stay in the fridge for up to 4 days before it goes bad.
If the turkey breast is cooked then the cooked turkey breast will last around 7 days in the refrigerator.
But if the turkey breast is raw then the raw turkey breast will last for around 4 days before it goes bad and should be thrown out.
If you notice the raw turkey breast getting slimy feeling or it smells bad then it's ready to be thrown out and if you try to eat it when it's spoiled then it can make you pretty sick.
If in doubt about the raw turkey breast or any other raw meat being bad then throw it out and don't risk getting sick.
If you want to keep the raw turkey breast or even cooked turkey breast longer than 4 days you should freeze it instead.
In the freezer the raw turkey breast or cooked turkey breast can last as long as 6 months to a year.
After 6 months the quality of the raw turkey breast or even cooked turkey breast is diminished but it still is safe to eat.