I know it sounds so stupid but here is the thing:
Couple years ago I downloaded the Calibre 2.27.0 to read e-book and then today I design to upgrade it to 3.30.0 but somehow I deleted the 2.27.0 installer already
So when I upgrade my calibre, it requested me to show the 2.27.0 installer to it which I can't and now I can't either upgrade it to 3.30.0 nor open the old 2.27.0 calibre. What should I do now?
p.s. I tried to delete the whole calibre programma but my pc want the 2.27.0 installer too. (so can't delete it now)
p.s.s. I have downloaded a 64bit calibre 2.27.0, it works but I still can't use it to upgrade.