I have experience on using inkscape, but I can't seem to find how to fix a seemingly fairly trivial problem I have.

As you can see, the icons in the sidebars, as well as the bottom and the top tabs are much smaller than usual, and I have not experienced this problem before.

Are there any ways to fix this?

Nizam, you need to attach the image locally so we can view it.

If you go to Preferences > Interface you can set the icon sizes to smaller, small, large, larger.

However, you have to restart Inkscape for the change to take effect.