Usually, there is one included with the software that comes on your PC.
Mine was in the same bunch of programs under the heading of
office tools.
My pc is kinda old but the one that came with it was called
Microsoft Photo Editor.
Try clicking on a file with the extension of jpg
What ever opens up a file like that will most likely be able to resize it
Now that I think about it ... You can use Microsoft Paint to do it
Grady