I have a website which is working well, but now I want to change the appearance of it not the contents, so I just want to remove the whole files in hosting company and upload the new one with same content but different appearance, will this be a problem for my search engine rankings and any related ?
Removing all the files could essentially "reset" your rank.
Why remove them all? Modifying the template would be a better idea, you’d keep all the information on site, same URL structure, etc without upsetting the rankings.
Obviously any major change to your site can and will have an effect on your ranking, it just depends on how much.
If you’ve created a template and can change that (eg the look) then you stand a better chance of maintaining any ranking you’ve achieved. You don’t want to knock out your foundation.
That said, if it’s a new site it won’t matter so much.
Also, are you keeping the same URL or changing it?
Is your site currently in a non-SEO friendly format (eg flash) that you’re updating to a more friendly version? If so, do it.
Anther consideration is the end user. Does your current site navigate easily? How about your new one?
As much as ranking is important you must keep in mind the people using your site. If they like it you’re on the right path. If you only build for search engine spiders you could be missing out on myriad opportunities.