If underwear, bed sheets, or towels were laundered during the 9 days, is it permissible to benefit from (wear or use) them during the 9 days?
I had the same question and found this answer online: The bottom line is: R' Moshe Feinstein rules that while one should not wear freshly laundered underclothing during the nine days, if one doesn't have any (preworn) underclothes he/she can wear whatever they have. Link to above article: http://www.vbm-torah.org/3weeks/mf.htm
I'm not sure if this ruling includes bed sheets, however I found another website which discusses this: Here is the link: http://www.beingjewish.com/yomtov/mitzorim/ninedays.html This website also says that you can wear 'any' laundered clothes (and use fresh linens)if nothing else is available.
IMPORTANT: One should always consult a Rav with any hallachic questions and not rules for himself/herself. Asking through a website is not the same as asking directly to a Rav, which is the proper way. Hatzlocho! May we be zoche the geulah hasheleima when these days will be converted into days of rejoicing and happiness! May it be speedily now.