Mavin,
There are several things that may be wrong with your simple oscillator (or sawtooth) circuit. First, you are using a basic NPN device that may not be suitable for your circuit. I would suggest choosing an NPN that has the characteristics you need for the circuit. I verified with the model you were using, however, I do not recommend that NPN.
Next, the simulation parameters need to be altered for you to get a simulation. The default parameters for TINA-TI do not like oscillation circuits, so you need to change some of them. They are marked in red in the picture below.
Finally, the capacitors you are using are too small for an oscillation to occur. If you increase them to 20n, you will see the oscillation.
