What was used to helps scholars decipher hieroglyphics?

The key to the translation of heiroglyphics was the discovery of the Rosetta stone. This was found by a Napoleonic soldier in Egypt in 1799. It was made around 196 B.C. and contains an edict of Ptolemy V. Essentially, the same text is written in three different scripts: heiroglyphics, Demotic, and ancient Greek. As we never lost the ability to read ancient Greek, the stone enabled scholars to start figuring out what the ancient Egyptians wrote.