Sorry if this is a bothersome post, but I have looked around, a lot, and cannot find a link, that works, to download this library. Several tutorials on youtube show how to use an I2C chip with a 1602 display. These tutorials state that the library mentioned above is needed, and they all post the same link to bitbucket that does not work.
There is a much newer and better library available for I2C displays that use the hd44780 controller (16x2 and 20x4). It is the hd44780 library by Bill Perry. It will auto detect the I2C address and the pin mapping between the LCD and the I2C backpack. It will work with PCF8475 and MCP23008 I2C expanders. It is far and away a better library than any of the old LiquidCrystal libraries. It comes with extensive documentation and example code.
For an I2C LCD display to work, the I2C address and the I2C backpack to LCD pin mapping must be correct. If the library default settings for either or both are not correct the LCD will not work. You can try to figure out the right pin mapping and use an I2C scanner to find the address, but if you install and use the hd44780 library that is done automatically by the library.
Install the hd44780 library. The hd44780 library is the best available for I2C LCDs. The library is available in the Library Manager. Go to Library Manager (in the IDE menus, Sketch, Include Libraries, Manage Libraries) and in the Topics dropdown choose Display and in the Filter your search box enter hd44780. Select and install the hd44780 library by Bill Perry.
The class that you want to use is the hd44780_I2Cexp class. There are examples to show how to use the library. The nice thing about the hd44780 library is that it will autodetect the I2C address and the I2C backpack to LCD pin mapping.
In the examples, there is a diagnostic sketch that will help us to help you if you still have trouble with the display. Run the diagnostic sketch and post the results.
If you have an example or code that you need to use that requires the fmalpartida library, post the code and I will help to fix the code to work with the hd44780 library if you would like. The hd44780 library is still maintained and the author is often on this forum.
I wonder why?
There is an older version of the repository on fm's github page but it wasn't up to date with the bitbucket version and there were many updates, including correcting the licensing to GPL v3, in the past few years that were not pushed to github.
I guess I need to increase the priority of adding 2 wire and 3 wire shiftregister support and ByVAC device support to the hd44780 library package.