If the .U3D file is known to your system, it is possible to open it by double clicking the mouse or pressing ENTER. This operation will start applications associated with the .U3D file installed on your system. If the system encounters a file for the first time and there are no relevant associations, the action will end with a system’s proposal to find the appropriate software on your computer or in the Internet.
Sometimes it happens that the files of the .U3D type a wrong program is assigned. This can sometimes be the result of the action of hostile programs such as viruses and malware, but most often it is the result of an incorrect association of an application with the .U3D file extension. If, during the operation of a new type of .U3D files, we will indicate to the system a wrong program, the system will erroneously suggest its use every time it encounters this type of file. In this case, try to re-select the appropriate application. Right-click on the .U3D file, and then select from the menu the option
"Open With ..." and
"Choose default program" . Now select one of the installed application from the list above and try again.
If our system cannot cope with the .U3D extension and all the automatic and semi-automatic methods to teach it have failed, we can only manually edit the Windows registry. This register stores all information about the operation of your operating system, including file extension associations with programs to support them. The REGEDIT entered in the window "search for programs and files" or "run" for older versions of the operating system, gives the access to the registry of the operating system. All operations performed in the registry (even those little complicated for the .U3D file extension) have a significant impact on the operation of our system, therefore, before any modifications, make sure that you have a copy of the current registry. The section important for us is the key HKEY_CLASSES_ROOT . This manual shows step by step how to modify the registry, specifically the entry in the registry that contains information about .U3D file.
"search for programs and files"(in older versions of Windows this is called
"Run"), type the command
"regedit"and then confirm the operation by pressing "ENTER". This operation will start the system registry editor. This tool allows you to not only view the existing entries, but also to modify, add or delete them manually. Due to the fact that the Windows registry is essential to its operation, all operations performed on it should be done carefully and deliberately. Reckless removal or modification of the wrong key can permanently damage the operating system.
ctr + For the Edit menu and by selecting
"Find"look for the .U3D extension you are interested in by typing it in the search window. Confirm by clicking OK or by using the ENTER key.