A bank is a bank is a bank is a bank. It doesn't matter whether it is Islamic bank or conventional bank, you will lose money if you are going to lose money. Islamic bank is not a guarantee of capital preservation.
Infact, if you are looking for real preservation of wealth, invest in gold. Just buy gold bars and keep them. That is the only form of real preservation of wealth, regardless of effects of inflation.
However if you intend to use gold bars to flip a profit, then it might be a bad idea.
Read my post here
http://www.islamicboard.com/world-affairs/134279126-articles-islamic-finance-6.html#post1267584 regarding loss of wealth due to fractional banking, which is something that Islamic banks practise as well.
There are numerous guides out there to help make secure islamic investments based on islamic principles and make you a wealthy muslim.
My sincere suggestion to you is don't worry about your losses, infact use those as an expensive lesson and learn from them, but go ahead and invest using sound principles and a good wealth mastery guide for muslims.
Allah says to His Messenger SAW: "Tell them, O Muhammad, even if you had authority over the treasures of Allah, you would refrain from spending for fear of exhausting it.''