According to the following Toshiba website: http://www.toshiba.co.il/en/discontinued-products/satellite-l670-14f/
her laptops's system memory (RAM) comes standard as 3GB (2GB + 1 GB) DDR3 RAM (1,066 MHz), with a mximum capacity of 8GB (provided she also has Windows 7 64-bit installed). (I'm not sure if that 8GB max is for real, though, or it's actually just 4GB) If you can see only one RAM card installed, then the +1GB mentioned above was probably removed by someone.
When you tried adding another 2GB RAM stick into the laptop, did you check to make sure it was also DDR3?
Also, sometimes computers get fussy if the sticks of RAM are not exactly the same (same type, same speed, and even same manufacturer). If you really want to upgrade from 2GB to 4GB of RAM, you may need to purchase two new sticks (they should only cost about $20 dollars each).
If you go to the following Crucial Memory website, it will scan your computer and tell you exactly what type of RAM sticks you need to buy: http://www.crucial.com/usa/en/?gclid=CLqBz9L13sECFeVaMgodrmIA6g&cm_mmc=google-_-us-_-dram-_-null&ef_id=VBdTUAAAAflD6n0D:20141103170846:s
Edited by Torvald, 03 November 2014 - 12:09 PM.