about LOR

[Luma]

I tried all the ways, but don't seem to be able to contact them.

So, stick with the professional letter of reference you have and describe your research exposure in the statement of purpose.

One more thing... as I mentioned earlier, I have a great letter of reference (on paper) from my maths prof who taught me advanced mathematics, can I make use of it?

I don't think it will be useful because simply it's "out of context". Moreover, letter of reference are being submitted electronically these days and you better waive your right in viewing it in order to maximize its value.

We request that your three letters of recommendation are submitted electronically as part of your Electronic Graduate School application....

Not waiving your right to review a letter of recommendation tends to diminish the value of the letter.
Department of Computer Science

[McQueen]

Thanks LUMA.
I will try to concentrate on statement of purpose.