There comes a time when every DM needs to translate a written passage into a mysterious clue or script for their players to find and attempt to decipher. Sometimes you even need to do it on the fly, because you were caught by surprise. Either way, not every DM has the time to memorize a new alien alphabet, much less be able to use it in a timely manner. Fortunately the internet is a vast and wondrous place, full of bizarre goodness for players and DMs alike.
A common "magical" script that's freely available, is the Theban Alphabet, also called the Witch's Alphabet, said to protect the contents of the Book of Shadows from prying eyes.
You can down the Theban Alphabet font for free, here. There is even a real-time English (or language of your choice) to Theban translator on the page so you can write what you want and save it as a png file to print, or display on screen.
If you're interested in background, you can read about the Theban Alphabet, here.
The next font is the Fez Font. I use this for the alien language of an ancient race that no longer walks the world of men.. or so my players believe.
This alien font can be downloaded for free, here. Again, there is an on-line translator window that allows you to translate on the fly and save as a png file for printing, or screen display.
If you're looking for something a little different, I suggest the First Temple Font. This works as a nice script for non-human writing.
It can be downloaded for free, here. And, for your convenience, again an on-line translator is available.
A simple on-line search will help you find many freely available fonts. If there is no on-line translator available for the font you're looking for, simply download and install on your computer for use in your preferred word processor, or graphics program. Please do not ask me for help installing fonts on your computer. You are better off reading the help files that come with the programs you are using.