[LG Optimus L9 P760, P765, P768, P769] Acrules:
Look simple yet effective way..

The assumption that I started with was that some of the primary font file are corrupted by font installer. My solution focuses around font files.

You've "Font Installer" installed then I assume you must be having su binary added or your phone is rooted.

All you need to have is latest version of adb tool and if possible set of fonts offered by android system(stock). Both of these can be downloaded from android's developer site(under android sdk), just google for same.

[Phone detection]

I also assume that LG drivers are also installed in your system, as phone might had done this already at first connect. Else search for Drivers from LG support site and have them installed.

Following are the steps you have to follow

- Started my phone in recovery mode that is HOME + VOL UP then POWER until dialog saying in "Recovery" appears.[Not necessarily CWM or others, just the default one]

- Attached phone to system, system will install drivers wait until all drivers are installed successfully.

- Open command prompt as Administrator.

- Change directory to location where you have extracted the adb tool.

- Create a directory name fontsBackUp(here we'll backup fonts from your phone).

- Type following command to check whether adb has detected your device[Make sure only your android phone is connected]

adb devices

- If above command lists your phone, then proceed otherwise check the connection properly.

- First part backs up font files present on your phone, just to make sure that we don't change any thing unintentionally.

Font files on your phone will located at "/system/fonts" location. To check this type following command on cmd prompt:

adb shell	[Takes you to adb prompt]

su	[prompt change to # from $]

ls system/fonts/	[All font files will be listed.]

- You need to make copy of these files, for that execute below command:

CTRL+C	[To make sure we don't execute command in adb shell][To get back to windows prompt.]

adb pull /system/fonts/ fontsBackUp	[This will copy all fonts file from your phone to PC]

- Make a folder named "fonts" just at the same level and put all font files from fontsBackUp to it.[Simple Copy Paste]

- We'll make changes in this folder(fonts).

- Now take font files that you have downloaded for your version of android(As I mentioned above) and over-write on the top of files that you've

extracted from phone(in fonts folders). Just replace the duplicate files.[You can use font files from your Windows 7]

When you are done with replacing, time to copy files back to phone. Use following command for same:

adb shell

chmod 777 /system/fonts

CTRL + C	[Back to Windows prompt]

adb push fonts /system/fonts [adb will copy font files back to your phone]

Note: Make sure you replace Roboto font and all other variants of it.

Just switch off your phone and start it again, there you go! phone should start as normal.

Note: If you've hard reset your phone assuming that will fix the problem, phone may a take little longer to start just be patient.

If you are unable to find default fonts for android or latest adb tool, let me know I'll upload it somewhere!

Above method solved my problem, phone started normally without flashing ROM.

Also, things suggested in this post by other members are equally relevant. All depends on your choice!