Need vb.net expert assistance

[Sora]

Hi , i have made a vb.net windows application project

and tried to change the .net framework into older versions like 4.0 , 3.5 but it wont change anyways

i got tired from trying so i've set it back to .net framework 4.5 then tried to compile but now it gives me same error i get when i try to change .net framework version into older version this error wont go and now i cannot compile my project , if you're an vb.net expert i would appreciate it if you can help me .

[JerrySiegel]

Once you convert a .net program from 4.5 to older version the whole structure of the program is changed.

[Sora]

Yeah , and here's the problem i may have to re-create the whole project again , nevermind i've done that ...