Had surgery 2wks ago to remove ganglion from back of hand. Stitches were removed last week now have bump where cyst was. What is the bump from?

Several possibilitie. Could be several things: 1) inflammatory residual, which should go down in time, use ice pack or moist heat, whichever helps more), 2) Local infection, but redness and warmth would be characteristics. If that's the case antibiotics might be needed. 3) Problem with the surgery, less likely, but would necessitate follow up with the surgeon.
Not sure . Suggest you contact your surgeon in case it is infected.