How I can convert a .SLDPRT file to IGEs or Parasolid, with out using Solidworks?
Use GrabCAD Workbench. Upload you sldprt file to workbench then you can right click on the uploaded file and select "download as". You can download the file in the format of STEP, IGES, STL, Parasolid, ACIS, JT, or VRML.
If your still struggling I'd advise you to check out my tutorial for converting files in Workbench
How to convert CAD files in Workbench