Increase in not found errors message in webmaster tools

[helenp]

Hi, my site has fallen (english section) and in the last 14 days I got this message twice:
http://www.example.com/: Increase in not found errors

My site is 10 years old, and often I delete pages, and I dont give any special error as this happens often,
so now I have thousands of not found errors, and many pages are years old, and Goggle has still not dropped them. What should I do with them?
Can this affect my ranking?
Thanks
.

[edited by: Robert_Charlton at 11:20 am (utc) on Jan 8, 2013]
[edit reason] examplified domain [/edit]

[helenp]

Thanks all, I am so appreciated, this morning I checked google webmaster tools and saw the exluded pages instead of dropped number of pages increased them....with about 8000 pages.
Then I went to google.com searched with hl=en and wow, my homepage is back, not on top but at the end on FIRST page....
Thanks again everybody.

[helenp]

Puf, not sure if to open a new thread as this is so long, however I dont get how the not selected pages keep increasing.
When I changed the soft 404 to a real 404 and took away the redirection to homepage for the 404 page, I expected the not selected pages (with equal content) to stop increasing and finally drop pages, but it keeps increasing.
On the 6/1 there was 51.210 pages,
I think I did the changes on the 8/1
On the 13/1 65.972 pages
on the 20/1 71.793 pages
and yesterday 27/1 79.224 pages....
Is this normal that it keeps increasing?

And by the way, the homepage is not back, as least not on the most important search keyword, suppose was a glitch.
The strange is that it also reported 2 404 soft error, when I have not had a soft 404 page since 8/1
Thanks

[helenp]

I didnīt want to reopen this large thread, but I cant open a new one.
Short resumen of what happened:
On the 6 januari i had 6.872 soft 404 errors, indexed total 626
Not selected 50.025
Pages bloqued by robot 95
On the 8th januari, the 404 error page was changed (redirecton to home deleted),
also I added absolute links between the directory as the 6000 404 error where due to googling mixing directories due to not having the / before a directory.

My site is now root relative and not document relative and have absolute links or links like /folder/page.htm

However the excluded pages now called ever indexed after GWT chang keeps raising.
Why does it keep raising even though everything is fixed?
Could the drop for homepage before in english now also spanish be due to this?

This is the grafic for ever indexed pages (before exclueded pages)
2 dec 1853
9 dec 4553
16 dec 7353
23 dec 15.552
30 dec 28.675
6 jan 48.830
13 jan 57.738
20 jan 71.315
27 jan 77.704
3 feb 85.651
10 fec 88.193

I have at the moment 0 soft 404 errors and
8.465 (cant be found) 404 errors.

Its really desperating

any ideas of what more can be done?