Cannock-based Newlife was left with the shortfall as it continued to run vital services – despite fundraising events and stores being closed.
Now the charity, which helps disabled and terminally ill children, has called on people to help get more stock into its stores to raise vital funds.
Sheila Brown OBE, co-founder and CEO of Newlife, said the pandemic had been a "huge blow" to the charity as called for people to volunteer their time to help.
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She said: "We have an extremely loyal team of volunteers but we desperately need more to be able to ensure we can get as many fashion and homeware items as possible processed so they are on sale in our stores rather sitting in our warehouses.
"Having to close all of our shops for three months during lockdown has dealt a huge blow to our income, which we desperately need so we can support families in crisis.
"But we’re delighted to now be reopening our stores and want to make sure we are giving customers as much choice as possible in the items on sale so they can help us bridge that shortfall.
"Whether you’re a furloughed worker or have a few hours to spare, this is a great opportunity to be part of the recovery of the pandemic in a friendly atmosphere and most importantly you’ll be changing the lives of disabled and terminally ill children."
People can sign up at a time to suit them – with tasks including removing brand labelling from donated items and hanging up items.
Anyone who completes more than 20 hours of volunteering will receive a discount in the charity's fashion and homeware stores.
Volunteers will be invited for a two-hour trial shift and then asked to volunteer for at least two to three hours when they can.
Free refreshments will be provided and travel costs can also be claimed – with people asked to call to book in a slot when they're free.
Scott Johnson, who joined the charity as a volunteer, is now a member of staff – and has urged others to follow in his footsteps and help out.
He said: "Volunteering at Newlife let me see what it was like to be part of a team again and gain new skills.
"I also knew that Newlife provides services to disabled children and their families which are desperately needed and being part of that really appealed to me.
"I still see all the volunteers here regularly and everyone who comes gets so much out of it, they really look forward to coming in. Volunteering is one of the best decisions I made."
It comes after Newlife reopened its Superstore and Home Store in Cannock as well as the store in Yardley, Birmingham, on Friday.
A range of measures – including strict social distancing and cleanliness – have been introduced to ensure staff and customers are protected.
Surplus items, faulty products and customer returns are handed to Newlife from major retailers instead of sending them to landfill.
All profits generated from the sale are used to allow the charity to provide essential specialist equipment to those in need across the UK.
Newlife operates a nurse-run helpline and is the UK's leading charity provider of specialist disability equipment – and has helped more than 22,500 children over the past three decades.
Anyone interested in volunteering should visit newlifecharity.co.uk/volunteering and apply using the contact us form on the website.