hi this is impeller water pump can you help me to repair stl to cad model in geomagic design x 2015.2.0 with video recording to teach me because i am student .

STL files, in general, aren't very convert-to-solid-model friendly due to all the triangular facets of the mesh. It might not be a problem if all the surfaces are planar, but if there is curvature to the parts and one does manage to convert the STL to a 3d solid model, it may still have all the mesh faces and look very coarse, and probably won't be particularly useful in that form.

I don't know about geomagic design, but with Solidworks, if there are more than a certain number of triangles, it cannot generate a solid from it and will only import the STL as a 3d graphic.

There is 3rd party software that can help with the conversion, but that too can be hit and miss.

Long story short, STL files suck for trying to create geometry from and the best bet is to try to find a STEP or IGES file to start with.

I'd suggest looking on Youtube and similar sites for training and demo videos. The skills learned in those will apply to this specific project as well.

Before attempting to fix it, I suggest re-scanning it. If you start with a good scan, fixing it will be easier, and more accurate.

Because this part is essentially a repeating pattern, You should focus on scanning and repairing a single vane. Once finished, it can simply be patterned. The other vanes will need to be scanned to get their position, and overall part dimensions.

Looking at the data in the scan, and considering the data missing, the scan does not make sense. You are going to have to guess at what the missing data is/was. It is simply not worth the time it takes to repair this data, as a single wrong guess will ruin the final model.

Also, working in Design X (as opposed to SolidWorks) is a pain in the ass. It is great that Design X can create model edges from scan data, but it is also quite painful to use as a modeling program.
I usually try to create reference sketches and planes in Design X, then import those to SolidWorks to do the model making