Ideally you can restore whatever you‘ve deleted from a backup.
If you removed the standard Python installation of macOS, boot into the Recovery Partition (if any) and reinstall macOS from there. This should leave your other files intact, it‘s not a bad idea to do a backup before nevertheless.
Alternatively, you can through Homebrew.
Once Homebrew is installed, run:
brew install python@2
That won't likely install the same 2.7 revision you were using.
If you need an exact match, or don't/can't use Homebrew; I'd build it from source (if so, comment for further instruction).
Python 2 is end of life by January 1st 2020. Please don’t use it unless you are sure you are using an OS default.
If I am not in mistake, as of June 2020 macOS
10.15.4 (i.e., not fully up to date) is still at Python 2.7 (
If you are at
10.15.5 or later you are welcome to comment your mileage.