how can I instal ver 4
You can download and install MT4 from the brokers' websites only (find MT4 broker and install from their website).
If you had used this (before posting), you would have found (among 400+) Where to download MT4? - General - MQL5 programming forum (2017)
How To Ask Questions The Smart Way. (2004)
How To Interpret Answers.
RTFM and STFW: How To Tell You've Seriously Screwed Up.
It has been years since you could download MT4 from Metaquotes. You can only get it from a broker's website.
Where to download the orginal MT4 installer - MQL4 programming forum (2018)
Team
I download version 4 but when I installed I saw it is version 5,
is there any way to instal ver 4?