只能粗略讲一下，想再弄清楚一点，建议查词典（牛津、朗文、柯林斯一类的）~
1 seek（for) sth: 跟look for意思差不多，牛津上的解释就是：to look for[第六版]，[I, Ipr esp passive 尤用於被动语态, Tn] ~ (after/for sth) look (for sth); try to find or obtain (sth) 寻找; 找到或得到（某事物）[第四版]
2 look (for sb/sth)： to try to find sb/sth 尽力寻找，寻找的东西可抽象（如solution），也可具体，见下：
I can't find my book-I've looked everywhere. ◆ Where have you been? We've been looking for you. ◆ Are you still looking for a job? ◆ We're looking for someone with experience for this post.）
3 前面两个（seek for、look for）都是强调“寻找”这一过程，find强调结果——“找到”
4 search，意指“搜寻、搜索”，牛津第四版的解释为：搜查（某人）; 细查（某物或某处）以搜寻某人[某物]; 搜索，通常用search (for sb/ sth)的结构，同样不知能否“找到”，只是强点要“寻”
参考资料：牛津词典第四版、第六版