如果卸载了.net4.5 服务器黑屏 用下面命令 开启服务器桌面版（每个/前带空格）
dism /online /enable-feature /all /featurename:servercore-fullserver /featurename:server-gui-shell /featurename:server-gui-mgmt
window server 2012 安装 .net 3.5
在cn_windows_server_2012_r2_x64_dvd_2707961.iso，sources下将sxs文件夹拷贝到C盘根目录，
sxs文件夹 可自己提取，也可网上搜索网页共享的
dism.exe /online /enable-feature /all /featurename:NetFX3 /Source:c:\sxs
卸载 .net 4.5
dism /online /disable-feature /featurename:IIS-ASPNET45
安装.net 4.5
dism /online /enable-feature /featurename:IIS-ISAPIFilter
dism /online /enable-feature /featurename:IIS-ISAPIExtensions
dism /online /enable-feature /featurename:IIS-NetFxExtensibility45
dism /online /enable-feature /featurename:IIS-ASPNET45
注册asp.net 2.0 到IIS
cd C:\Windows\Microsoft.NET\Framework64\v2.0.50727
aspnet_regiis.exe -i
附 sxs文件
win10：
链接：https://pan.baidu.com/s/1FhbTkVoXh-149voHUSZ-nQ
提取码：3pqr
server2012：
链接：https://pan.baidu.com/s/1AoHhAevBwFmxppslVSO_lw
提取码：3oze
server2016 ：
链接：https://pan.baidu.com/s/1COH3ABtZYRaUygfRrd0_Ew
提取码：mka5