My daughters DS bottom screen is white. It turns on but the screen is just a white screen. She can not play any games on it. Any suggestions?

It would seem the lower screen is broken in some way. If the DS sustains a severe impact, it can damage either the screen itself, the connectors to it, or even the processing unit in the system.

You can choose one of several options.
1. Try locating a replacement screen. These are usually found on parts websites for low cost as a pair. The downside to this is that you need to disassemble the DS unit yourself, which requires a special screwdriver (called the tri-wing screwdriver). But if something else in the unit is broken, you will have spent extra money for nothing.

2. Contact Nintendo and find out the cost for repairs. (can be near $100 USD depending)
They will ask you what the problem is, possibly offer extra solutions, and give you an estimate on the cost. Then all you need to do is send it to them and they will repair the unit for you.

3. Buy a new unit. This is the least favorite of the options, but in the long run, it may end up costing less, or very close to any repairs needed. Save games are all managed by the game cards themselves, so you will not lose any data through this.