I am at a loss for words to express my distress on the death of ...
对于某某的噩耗,我不知道如何表达心中的哀痛.
...will always be held in high esteem
某某将永远受到尊敬
Just take one day at a time
节哀顺便
Please convey my sympathy to his/her/your family
请向他的/她的/你的家人传达我的关怀
Please accept my sincerest condolences on this sad demise of...
请接受我对某某逝世的真诚哀悼