Letter 'A' gone!!!!!!

[ashhab2010]

i had recently installed Bisigi Themes and Cairo dock after which the letter Capital A has gone ... it just appears as a black box with some smudges on it...i dont know which of the two caused it... bfore installing them the letter was visible ...plz help:(:(

[Coltman151]

Sounds to me like the font you are using doesnt have a capital A.

[ashhab2010]

yeah , thanks never thought that could be the case... but how come the font changed??... i never touched that setting, can it be possible that the font got corrupted??? the font was named 'Ubuntu'

[ashhab2010]

the problem has again appeared!!!! i had changed the font to something else and then the letter 'c' & 'K' had the problem...
i dont think it might be long enough before all my letters are gone :-)... hurry plz