There are a couple of ways of doing this. One would be the EasyOpen extension although be careful with that as I think it stops you from deleting posts using the drop-down menu on the Edit page. Easy enough for what you want though. Just get a list of all the entries to close and close them and once finished just turn off the extension.
Another way would be using a SQL query although you obviously need to be more careful running these types of things.
Alternatively you could always just hard-code the weblog tag to only bring back the entry_ids that you want to see and that way you don’t have to change any status at all.
Something like this :
{exp:weblog:entries weblog="default_site" entry_id="1|12|14|45"}
<h2>{title}</h2>
<p>{body}<br />
{/exp:weblog:entries}
Obviously you will need to find out the entry ids of your own entries that you want to show but this might be another way of going about it? Another alternative would be to create a new status instead of just Open and Closed and then change the entries you want to show to that status and then provide the status=”“ parameter in a weblog tag instead.
All valid ways of going about it really just depends on which you prefer.
Hope that helps a bit.
Best wishes,
Mark