Looking for accommodation in Dusseldorf

Your budget is very high, so it won't be a problem finding something quickly.
But since all listings are in German (of course!), you may want to engage an English-speaking property agent who can translate for you.
Good luck!

1)
Hello Some of them are:
immowelt.de
immobilienscout24.de
wg-gesucht.de(there are also listings here for independent house)

2)
Use Google chrome which has: Translate to English option 

actually since last year I am looking for an apartment for my family ,the problem is that ,I need to continue my work in my  own clinic in UAE.dubai but the family will live in Germany .
so I don't have salary certificate to provide to agent in Germany and they are not accepting it .
how can I solve this issue ?

Every German landlord is applying his own selection criteria - and as you encountered they usually include a check if the tenant can pay the rent or, if not, if it can be recovered by legal proceedings (which can unfortunately not reach foreign income sources).
You can overcome this by offering to pre-pay the rent for the period you want the flat.
Also, many landlords might reject you because they are conservative and share the common paranoia about Muslim fanatists. You can lessen their fears by showing that you are not Muslim, or at least a modern, open and flexible one.