You need to start over. To get a culture to grow properly you could do the following (there are other ways, but this is how most do it)
Setup. You will need a light source (fluorescent bulbs work well), an air pump, soft air line tubing, rigid air line tubing, 2-liter clear bottle, phyto fertilizer and salt water.
Rinse out a 2-liter bottle and add freshly made salt water with added fertilizer (i recommend using a fertilizer formulated for phytoplankton to reduce the amount of nutrients added to the tank). Do not use anything that has come in contact with tank water. Drill a hole on the lid large enough for the rigid tubing to fit through. Let the water bubble overnight with the light source off.
You MUST use a live source for a start. Something sitting on the shelf at room temperature at the LFS is probably not alive.