If it's not set already, try changing your windows scaling to 100% (no guarantees this will work). And make sure your graphics driver is approved by SW
Agreed to Solid Air - some of it showing in the screen shot - seems like the video card problem !
This problem has to do with the Windows DPI settings being at a certain value (probably around 175%) in service packs of SOLIDWORKS 2016 before SP03. I can tell you are running an earlier service pack than that because your part icon is gray instead of yellow (we changed it later in the service packs). The problem of the icons being missing in the tree at a small subset of DPI scales was fixed in 2016 SP03, so please upgrade to solve your issue.
For future reference, I would suggest searching the forum. If I use the following search for "icons missing tree" then the first couple of results have the solution already documented:
I hope this helps,
Thank you for your help. I fixed it by changing the DPI to 150%. I've tried to download the upgrade SP03 but i'm currently using a student version provided by my university and i don't have full access to the upgrades.
Thank you again,