If I lost my disk and turbotax 2019 is not on my computer, will installing a new turbotax 2019 download erase my earlier 2019 data?

[Critter-3]

No it will not ... the .tax2019 file is not housed in the program. 

[SteamTrain]

.....and, if the original tax file contains any state tax returns,  you'll need to start a dummy-tax return first...and get in it just  far enough that you download and install the proper state(s) you need in the program, before you attempt to open that older tax file.

[Opus 17]

Your tax data is stored in a file that usually has a name like “John Smith 2019.Tax 2019”, usually in your documents folder.  You can have many different tax data files, just as you can have many different word processing documents.  (The extension. “tax 2019” may be hidden depending on your system settings, but it must be there.)

Adding or deleting applications should not change the location of your data file. However, as mentioned above, you will need to install any state modules and you may need to start a blank return to initialize the program, before you will be able to open your existing data file.